Marvel is taking a page from DC's 52 by rebooting the whole Marvel line. New characters and all issues starting from scratch. This is basically telling us Marvel have become stale. They need a fresh crop of new readers. DC sales already crested a year ago with their last reboot. They too are looking for new ideas to stay on top.
The new books — about 55 to 60 in all, slightly less than Marvel
publishes right now — will each introduce new storylines. In some cases,
a new character will be wearing familiar costumes, or will have moved,
or will have significant shifts in their relationships to other
characters. Many of those changes will be shockingly big. (source)