Sooner or later, the Fantastic Four are going to to join the MCU. Clearly when Disney bought Fox, they considered all the potential gains (reduced competition, Deadpool/X-Men movie revenue, The Simpsons, Blue Sky Studios...) but as soon as news broke all Marvel fans cared about was getting the Fantastic Four up on the silver screen.
There’s excitement for X-Men too, but the mutants get a bit of a pass for now. Dark Phoenix is still to come out and Fox have given us great movies from the franchise like X-Men, Logan, Days Of Future Past and both Deadpools. Yes, there’s been duds, but don’t forget the MCU gave us Thor: The Dark World too.
The Fantastic Four, on the other hand, has had three chances with two different casts and produced duds every time. There were some bright spots (to be addressed later), but overall the movies were severely disappointing and fans have ran out of patience.
The only question which remains is how to get them into the MCU itself. Yet another origin movie? Teaming up with another hero? A villain ushering them in? Something to do with Thanos? Marvel has lots of possibilities at their disposal.