Not so long ago, the idea of Marvel ever getting the chance to use the third-party owned characters they had sold the rights to (foolishly and way too cheaply) seemed entirely impossible. But then all of a sudden, Sony and Marvel did something magical and a whole new world of hope was opened up. Spider-Man came home and suddenly everyone started getting all misty-eyed at the prospect of Fox maybe lending Marvel The Fantastic Four or maybe a couple of lower level mutants.
Even with the rumour-mongering around such things, the likeliness of it actually happening was pretty low. Fox didn't need the help, with the X-Men franchise still broadly lucrative and Fantastic Four able to be sat on for a while with enough goodwill in reserve to make the inevitable reboot a viable option.
Things have changed now though, and the news that Fox and Disney have discussed a huge deal that would lead to Marvel regaining the rights to some key characters they've so far not been able to use in the MCU has changed everything again. Sure, the deal might have hit a snag, but we wouldn't be all talking about it if it wasn't still possible. Hell, we wouldn't even be aware of it.
So, there may come a day in the not too distant future whent he MCU gets an influx of new characters, and there are immediately a strong group who stick out as the most exciting...