Well, we know the Marvel first family are heading back to their parent company, barring any unforeseen last-minute twists in the tale of the Disney/Fox buy-out. And according to some pretty big hints since that deal was first announced, Marvel would actively look to bring the Fantastic Four to the MCU (somehow), rather than rebooting them as a stand-alone.
They're the crown jewels of the Marvel universe, even with two failed film franchises, and the idea of them sitting inactive when Marvel Studios have the rights is just impossible. It's a matter of when not if.
Marvel nail the correct tone without going too gritty or too goofy (the two things that messed up the Fox iterations), while using the Comics arm of the company to bring the team back with a premium line comic. Crucially, they need to hire someone like Brad Bird, Phil Lord and Chris Miller or Matthew Vaughn, who could marry nostalgia with heart.