Hmm, I figured they'd try and build around the X-Men. Granted they might not want to since the Fox X-Men stuff is still going on, but I feel like that would offer a change of pace. I don't think X-Men or Marvel fans would mind that much as the X-Men movies have been considered kinda duds I thought. They'd do some things right but ultimately were lacking (no clue why Mystique kept playing such a significant role; ok well "woman in just blue paint" obviously and the big names that played it, but still).
There's plenty to overlap with the established MCU stuff as well (a Hulk vs Wolverine, especially if it included Deadpool, should do well). Captain Marvel provides an avenue to do a proper origin story for Rogue. I think Gambit could do well. And stuff like the Phoenix/Dark Phoenix saga, would give them opportunity to mix in the cosmic stuff (but that's not likely seeing how they're just about to release the Fox take on that).