I pretty much guess the "Alien 5" idea is discarded, they dropped numbers after Alien 3 and probably they don't wat people to remember how many movies they have done.
It could be Alien + a subtitle. Or something entirely different...
What would you suggest?
I would say Alien Returns could be a good title. Sounds much like Superman Returns, and in my country Aliens was titled Aliens: El Regreso (Aliens: The Return), but I think it could work. After all, it's a return after a long time without an Alien movie.
If Ripley's involved, probably Ripley Returns, Ripley vs Aliens (OK, maybe not that one) or plain go Rambo with a "Ripley" title. But who knows, the "Alien" title is important to market the movie, prrobably Alien: Ripley Returns? Alien: Ripley?
For more alternate titles to the ones I provided, just add an "s" at the end of Alien for movies with that word on it:D