I'll try, and I'll even add an option.
Chances of Fox making a new FF movie before reversion date: 10%. They've done it before, and Fox is notorious for not wanting to give up their properties. However, Fant4stic was such a financial failure it is hard to justify trying again. It would have no chance for success.
Chances of Fox making a Fant4stic sequel: 0%. Not happening. If they try again it will be a reboot. No matter what Kinberg says.
Chances of Fox making a Silver Surfer movie before reversion date: 5%. They have never shown interest before and even now they bring up Fantastic Four in interviews and such, never Silver Surfer. It isn't even certain that a Silver Surfer would allow them to keep the rights and it would cost more than Fox is willing to pay. Not totally impossible, but I think it is even less likely than simply rebooting Fantastic Four again.
Chances of Fox and Marvel making a Sony-type deal before reversion date: 1%. Even that might be too high. There is no reason why Marvel should want to do this. The Fantastic Four brings nowhere near the value that Spider-Man does. Not even close. However, there is a very tiny chance this could happen if it is a deal for the X-Men and the Fantastic Four just happen to get included as an afterthought. But that doesn't really make sense for either side.
Chances of Marvel making a deal to get the rights outright before reversion date: 34%. A fair shot of happening, but I don't think it is the most likely outcome, especially as time passes. Marvel has all the leverage and that presents a problem when it comes to cutting checks. And the closer we get to deadline, the less they will likely be willing to offer if they think they can get it for free. Fox executives meanwhile are likely going to try to save their own skin by kicking the can down the road as long as possible. That said, Marvel may be unwilling to take chances and a desperate Fox could be willing to accept any offer as well. So it remains a good possibility.
Chances of nothing happening and rights quietly reverting in in 2022 when Fox fails to begin production by deadline: 50%. The most likely outcome. Fox hangs onto the rights as long as possible, at which point they have to make a decision. There are attempts to try and get a new film off the ground, but Fox is ultimately unwilling to flush that much money down the toilet and filmmakers avoid the project like the plague. The new Fantastic Four film ends up in developmental hell and the rights revert.