Oooh, this is interesting. Again, assuming the JSF gets smothered in the cradle (lets's say circa 2000), then you have some interesting possibilities. I'll try to keep it fairly realistic and not entertain too much fantasy (like the "FB-23", etc.)
I think the biggest one that you're forgetting on your list of possible alternatives, Greg, is the F-22 Raptor.

I think the USAF is going to get at least 300, maybe the 381 it wanted or more if it's cleared for export and they can keep the line open for another decade. Anyway, I'll give my thoughts in the order you proposed, again, trying to be as sensible as possible and not do my own personal "wish list".
- Royal Australian Air Force - Boeing F/A-18E/F Super Hornet
The boring (and most likely) answer here is that the RAAF would just get more Super Hornets. Even if cleared for the F-22 (which the RAAF would be), then it's doubtful they'd swallow that bill. I could be wrong, though. If the PLAAF is looking scary enough, the per unit price comes down enough, and the line stays open long enough, then an couple squadron F-22 buy is possible, but I still wouldn't bet on it. The F-15 would be a good fit, but I don't think it offers enough of a generational leap for Australia to operate it alongside the Hornet. I think a split Hornet/Eurofighter buy is more likely than a Hornet/Eagle.
- Royal Canadian Air Force - Boeing F/A-18E/F Super Hornet
Similar to the above, but I think the Super Hornet is even more likely. The Rafale would be an interesting option, but I don't find it too likely.
- Belgian Air Component - Lockheed F-16V Viper
The sensible option is something like an F-16V. Rafale would again be cool, but unlikely (more likely than any other nation on this list, though). Honestly, Belgium would probably be happier with this alternative scenario than the real world one.
- Royal Danish Air Force - Lockheed F-16V Viper
I think the F-16V is the most likely, but politics play a big role and I think the Typhoon or Gripen have more to offer in this category. They're certainly more interesting, but my money is still on new F-16s.
- Israeli Air Force - Lockheed F-22 Raptor
Israel would be pushing very, very hard for F-22s. I think the only world where they don't get them is the one where the F-22 is barred from export in this scenario, which I find unlikely due to political lobbying. More F-15s and F-16s are quite probable, even with a Raptor purchase, though. If the Raptor is not on the table, then I think Israel will be the lead customer for a seriously stealth-spec'ed F-15SE Silent Eagle.
- Italian Air Force - Lockheed F-16V Viper
They may outright buy new F-16s after their happy lease of the F-16A/Bs in this timeframe. I think Typhoon as dedicated fighter and F-16 as ground attack/SEAD Tornado replacement would be very sensible. More Typhoons in a more multirole configuration is an option, too--obviously--but I don't think Italy would want a single type fleet.
- Italian Navy - No replacement
Given the lower threat environment in the Mediterranean post-Cold War and the limited ranges, I see Italy going with upgraded Harriers until they can't fly them anymore, then retiring without replacement sometime in the 2030 timeframe.
- Japan Air Self-Defense Force - Lockheed F-22 Raptor
This is another interesting one. I think the F-22 buy goes ahead, Japan buys ~120 F-22s, then opts for either new-build F-15s, ATD-X-based F-3s, or (most likely) a combination of the two. Upgraded or new-build F-2s are possible, but I get the impression that the JASDF was a little disappointed with the F-2 and wouldn't want to throw good money after bad.
The real question is what would happen to the desired ship-borne aircraft role that Japan most recently bought the F-35B for? I think those plans don't ever come about in this world. I don't see Japan going full STOBAR or CATOBAR with Hornets and I don't think new Harriers would offer the capability Japan wants. I think this one just dies on the vine.
- Royal Netherlands Air Force - Lockheed F-16V Viper
I think the most likely option is new-build Vipers, likely assembled in Europe. While Typhoons and Rafales are possible, I honestly don't see it happening. I think the original NATO F-16 consortium from the 70s will just re-buy the F-16 again.
- Royal Norwegian Air Force - Lockheed F-16V Viper
Again, I think boring F-16Vs is likely, but a Nordic buy of Gripens is a possibility. Norway sometimes does some interesting stuff with its equipment, so Typhoons, Meteor-integration on Vipers, or Gripens are all options on the table.
- Polish Air Force - Lockheed F-16V Viper
Much as the Larry Bond fan in me wants to see Polish F-15s, I think more F-16s is the name of the game again here. Eurofighters or new-generation Eagles could happen because Poland really wants latest-generation tech capable of taking on anything Russia can put in the sky, as we've seen in their surprising enthusiasm for the F-35 currently.
- Republic of Korea Air Force - Boeing F-15SE Silent Eagle
Considering the number of types that Korea currently operates (KAI KF-16, Boeing F-15K, and--eventually--the KAI KF-X), a couple squadrons more of any of these would cover the gap left by missing F-35s. They might get F-15SE Silent Eagles if that variant becomes a reality. A more interesting option would be the Typhoon since it did so well in the F-X Phase 3 competition, but considering the fact that the F-15K won the other two phases and the F-15SE progressed well in the final phase, I don't find it the most likely. I don't see Korea getting F-22 clearance, but they've been moving up the US's priority list, so I could be wrong.
- Republic of Korea Navy - KAI KF-X
I'm inclined to repeat my comments for Japan's F-35Bs, but Korea's been surprisingly ambitious lately, and I'm wondering if they wouldn't try their hand at a carrier variant of the FA-50 (think Tejas) or KF-X (
à la J-31).
- Republic of Singapore Air Force- Boeing F-15SG Strike Eagle
By far the most interesting option here is Singapore option for the newer, stealthier, high tech Rafales that did so well in competition against the F-15, but I think 12 more F-15s is the most likely option here. F-16Vs and the more advanced F-15SE Silent Eagles are also likely (but still boring) options.
- Royal Air Force - Eurofighter Typhoon FGR4
Any of the American teen series would be seen as a retrograde step and offer no industrial advantage compared to the Typhoon, so I think they're all non-starters. I also think the F-22 is unlikely due to the pricetag and lack of industrial cooperation opportunities. A single type fleet may not be wise, but I see no realistic alternative.
- Royal Navy - Boeing F/A-18E/F Super Hornet
I think the RN sticks with the CATOBAR redesign of the
Queen Elizabeth-class carriers and goes for Super Hornets instead of Rafales. They're less expensive, offer greater commonality with the US Navy, and throws a bone to US industry after buying just Eurofighters for the RAF.
- United States Air Force - Lockheed F-22 Raptor
The USAF wanted more F-22s and this is a good way to get them. You'll likely have more of a high-low mix between F-22s and new-build teen series fighters. Fewer low observable fighters in this scenario, but I think a similar number of airframes overall.
- United States Navy - Boeing F/A-18E/F Super Hornet
The USN will really want a higher performance fighter than the Super Hornet and I think they'll start getting serious about it once the J-15 starts going to sea on PLAN carriers with J-31s expected to follow. I don't know if that will take form as a manned Gen 6 platform (I don't think the USN has the budget to go it alone, so that would have to be a joint project again) or a UCAV. I think the UCAV/loyal wingman scenario is the likeliest one. Boring, I know, but that's where the world is heading. In good news, I think some budget would be found to fix the Super Hornet's stupid wonky pylons.
- United States Marine Corps - Boeing F/A-18E/F Super Hornet
Easy transition from the legacy Hornet and already in the Department of the Navy's supply chain. This seems pretty straightforward to me. I think the Harrier is going to be extended in service until at least 2030, likely with at least AN/APG-66 radar, eventually replaced by the AN/APG-83 SABR. When it does get replaced, I think it would be either a non-stealthy STOVL or another UCAV (more likely, I think).
I'm sorry if these are the "boring" answers, but I think there's a lot of options for countries nowadays when it comes to defense spending. Without the F-35, that money flows easily and naturally to other programs. There's certainly opportunity for the Eurocanards to pick up more orders, but I think that a lot of countries looking to replace their F-16s will end up going with another US fighter, in many cases because they're spending US Foreign Military Financing dollars.
Cheers,
Logan