"But can we wait until they've released Alien v Terminator v Predator v Batman Requiem, please?"
Not before they release Tarzan v. Predator. Hey, that's a Dark Horse comic! I still wish Alien3 had been based on Alien: Earth War instead of ... whatever that thing ended up being. Anyway, I think it was DH who started the "X vs. Y" trend, though they themselves may have been inspired by the "Godzilla vs X" Japanese trend. And there was a "Superman/Batman: 05/05/2010" poster in I Am Legend... could it be they're planning on this?
Anyway ... I actually am looking forward for T4, as I've always wanted to see the "future war" in all its glory, not just 2-minute segments. Notice that T1 shows more of this than T2, for example... and it was actually left open thanks to T3, it isn't like "Pirates of the Caribbean 2" which was motivated to milk the cash cow.
Ah, the irony... I was once given the choice of re-watching T3 or Pirates of the Caribbean... I chose T3. When I was actually forced to re-watch Pirates, I fell asleep for almost the entire movie.