A few years ago, Spielberg would have been my first choice. Now, I’m not so sure. I don’t think it’d be right to go from two films directed by fans of Star Wars since childhood, to literally George Lucas’s best friend. Also he’d never do it.
The obvious choices would be JJ Abrams, Gareth Edwards, or (especially) Rian Johnson. However, I don’t know about any of them. Abrams most likely wants to move on to something different, and I don’t think Edwards would be that much a step up from Trevorrow directing wise. Johnson honestly seems like the safest bet, but I do think there is real value to having a different director for each film. Maybe he could write it though…
My first suggestion would be Brad Bird, though he’s busy with the Incredibles. I could potentially seeing them wanting Favreau but he’s got the Lion King. Del Toro or Jackson would be interesting choices, but I don’t know, they don’t feel right for Star Wars to me, for some reason.
If I had to make a wild guess I’d say Ava Duvernay. Would be a good choice at least.