Runaways is a movie they have had concrete plans for in the past, which strikes me as something more plausible for the big screen. Namor seems the biggest name, but he's more complicated to bring on screen due to Universal still having distribution rights.
2020 is right around when Fox's Fantastic Four rights expire if they don't bring another new movie. It is always a possibility.
I suspect whatever it'll be, they'll want to take a small break from the cosmic. I also feel we should all be prepared to be completely surprised.