I have a feeling that with the exception of Age of Apocalypse, we won't be seeing any Events that are more than 5 or so years old.
First of all, they are looking to bring in new gamers, not just older gamers.
Second of all, CAM mentioned the problems with the artwork.
Third of all, Age of Apocalypse can support a bunch of Event Supplement books because it introduces an entire alternate reality. Most of the other older events don't really lend themselves to new settings / rules / campaign features to the same extent... except maybe Onslaught / Heroes Reborn (which is the one of the storylines that bankrupted Marvel both fiscally and artistically, so maybe not the greatest choice for an Event book).
I could be totally off base here, but I think we are going to see a lot of recent stuff like Secret Invasion, Dark Reign, World War Hulk, Shadowlands, etc, and not too much old stuff like Secret Wars, Kree/Skrull War, etc.
It's too bad that everything is entirely Event based... that means it will be difficult, if not impossible, to run a extended, ongoing campaign (without a ton of creative writing on the Watcher's part), and it also means that it we won't see any new adventures (like the old TSR game have, such as Breeder Bombs, Gates of What If, Left Hand of Eternity, etc), only adaptations of previously published adventures.
From what I can see, the published materials for this game will be mostly geared towards promoting recent Marvel comic books, and allowing players to relive their favorite (recent) comic book storyline with little to no variation. For example, the Breakout Mini-Event is nearly beat for beat the same as the published comic book, except you can make some changes to the New Avengers line-up (perhaps swapping out the Thing for Luke Cage as the "Strong Guy" on the New Avengers, etc).
If you want to see any original Events, where you don't already know the beginning, middle or end, or any older Events, I think you'll have to create them on your own.
But maybe I'm wrong?