1. If I remember correctly Namco also said SC3 would be the last game.
2. Namco also said that there was NO possibility of vader coming to the 360 or yoda to the ps3.
3. SC4 sold quite a bit, this is Namco we're talking about I doubt they won't be making a fifth one.
4. The PS3 is supposed to be around for ten years, and Sony has said there is a good chance they won't even make a ps4, when SC5 is released it will be on the ps3, and given the ps3's current state, it will most likely be multiplatform.
5. If it is exclusive it may very well follow SC3's example, Give us several kick ass new characters and kick ass new single player and multiplayer modes, but give us a crappy as hell battle system so we can't enjoy it all as much as we should.
6. I'd like to think even Namco isn't willing to let a franchise like SC end with three star wars characters and one actual SC character.