"It's not an Alien prequel, it just has Alien DNA!"
I think anything's possible. But it's certainly encouraging that Disney is putting a great deal of effort into finding the right people.
At this point, seeing how they've gotten someone like Kasdan, I'd feel confident on a gut instinct that Joe Johnston will direct.
It's just weird thinking about Star Wars as this team-based effort, when for 30 years it all came down to Lucas. There of course was the EU, but in terms of the film saga the prequels seemed like a solo project. They lacked peer feedback that made the OT so fantastic and wonderful.
The mere notion of multiple people collaborating to produce the best possible foundation (e.g. the screenplay) for the films is something I haven't felt since...