Well, COIE combined the different earths DC had. Infinite Crisis isn't going to split them from what I've read and heard. Changes will be instituted to various characters and each book except Superman, Batman, Action and Detective will start with new #1's. So I don't think IC is going to be regarded as changing as much.
No, no, no!!! COIE did NOT combine the different Earths! All it did was shift our attention from the E-1 Multiverse to a NEW universe. We didn't even KNOW it at the time.
Just like comics fans didn't know that DC shifted from the Golden Age Earth to the Earth-1 until much later.
The merged Earth at the end of COIE is a different Earth than the Earth on which
Man Of Steel takes place upon, which is different than that of
Birthright.
There is STILL an Earth-2 that was UNTOUCHED by the COIE. The Multiverse was simply TOO BIG for the Anti-Monitor to realize that. For every Earth-1 he destroyed, FIVE of them survived!