All 3 I believe.
It may just be ALIEN and avp though.
They never said anything about it and considering they haven't even hinted or mentioned the idea of a Predator only game I think its just avp and ALIEN. Then we all know Predator only games suck cause Predator is completely dependent on ALIEN.
If they never said they'd consider a pred only game it's because they don't think it's going to be a success at this time, not that they can't make the game.
And no, predator is not completely dependent on alien. Or what ever.