So I'm going to predict that in the upcoming Annihilation mini-series (which I'm eagerly awaiting) Aegis and Tenebrous are going to be the big problem, not Annihilus. Annihilus wants to destroy all the life he considers a threat to him (which is apparently most of it), Aegis and Tenebrous seem more interested in destroying the entire universe. So we've got an Infinite Crisis situation, only done a little better I think.
Infinite Crisis gave us four crises, then revealed that the true threat was causing all of them. Of course, within the minis, we didn't get much outright evidence that there was another threat, beyond the two Luthors running around in Villains United, and the appearance of Pariah (anything else?). Personally, I still feel Villains United would have been better if Lex Luthor was running both groups, using the Six as a Boogeyman to scare people in joining the Society, but that wouldn't have fit the larger game plan, so oh well.
Annihilation seems to have simplified the idea a bit. There's one major threat - the Annihilation Wave - and it's actions (destroying the Kyln) have unwittingly unleashed the much larger threat, the two Galactus level beings that now appear to have Thanos on their side. So I figure that just like Infinite Crisis, Annihilus is going to be put on the backburner in favor of dealing with the real problem. Think about it.
Silver Surfer has joined Galactus to help him in his battle, and he's decided to stay clear of the Annihilation Wave. Super-Skrull, who would have kept going after the Wave, is gone. Nova is all set-up to have a major confrontation with Bug-Boy this week, which might just settle that, and Ronan doesn't seem to care about any of it. The Wave's primary source of food was destroyed, the attempts to harness the Power Cosmic are failing, the plan is starting to run out of steam.
I'm actually going to predict that Annihilus fills the Black Adam role of "Bad Guy Who Fights Bigger Evil" and ends up helping fight Aegis and Tenebrous. Because I'm sure they won't balk at destroying him too, and his whole scheme was to solidify his standing and lessen the chances of his doom.
I have to say I like Annihilation's strategy better than Infinite Crisis. It doesn't feel as buried in continuity, where you have to know about Crisis on the Infinite Earths to get why these Pocket Dimension schmoes are so pissed. Marvel seems to have said 'Screw it. Let's just create some new things to be the primary threat. All people will need to know is that they're really powerful and they want to end existence.' Which, when combined with the Nova Corps files in the back that explain who all these rarely used characters are, makes it a bit more accessible to a new reader. Of course, sales will tell whether that turns out to be true or not. The lack of recognizable, iconic Marvel characters may hurt sales, but hopefully it'll do well.