Ah, the return of Sargeras.
Don't worry, WoW will get to that eventually.
I actually doubt we'll get to deal with Sargeras in WoW. Maybe we'll be able to stop him from entering Azeroth, maybe we'll defeat him once more, but I really hope that Blizzard won't make the same mistake and kill of its main baddies in generic raids with cinematic cuts that are far from impressive (though, honestly, I did quite like the end of the Lich King raid).
WC4 will be made, that's for sure. I already discussed in another thread (
note to the admins: merging the threads would be nice, as we now have several split discussions on WarCraft 4, with no big difference between them or whatsoever) the reasons why we'll have WarCraft 4. Just like Star Wars, WarCraft Universe has become too big for Blizzard to let it die.
So, yeah, I tend to believe that Sargeras will make his return in the end of World of WarCraft, and we'll be left to deal with him in WarCraft 4. I already talked about possible races - Human Alliance and Orcish Horde are the two which are almost 100% sure (that's WarCraft after all), and I'd vote for Demons and Old Gods. Of course, Demons would make their return in a WarCraft-styled fashion - not directly as a playable race, but possessing a race (orcs and undead were the ones for now). As for the Old Gods, I suspect we'll either see Nerubian or Naga culture.
Heck, we might even see the Titans. Who knows. But one thing is certain - WC4 WILL be a continuation of World of Warcraft (come on, you didn't seriously think that Blizzard would debunk such a large fan-base just because a bunch of WC3 fanatics actually don't like the WoW story, did you?)
That said, I wonder if we'll be hearing anything from the Un'Goro crater in WarCraft 4, or the Tuskarr, or the goblins, or any of the other "funny" side stories.