So whilst mantle is a great feature, Johan/Dice/Frostbite/AMD (pick one or more choices) are not going to sort out the memory issues and therefore, anyone with 1080P or higher and 2GB is screwed if they want to go full details or anyone above 1440P and 3GB is also potentially screwed if they want to go full details.
Seems a bit lazy to me and donning my tin foil hat, is this AMD forcing/wanting their users to have to upgrade to a newer card to benefit from Mantle?
Edit:
Just to add, I can see that as a good business move in honesty and wouldn't blame AMD for doing that if that is even close to the truth.
Nope, AMD have encouraged Johan/Dice to rewrite their memory management implementation but ultimately it is down to them and it appears they will only do this for up and coming titles not existing ones ala Battlefield 4 or Plants Vs Zombies. Plants Vs Zombies does have much lower vram requirements, so it is less of an issue there. However my 1gb 7770 can only run 1200P on low details, any higher and i exceed the vram limit. I can just about run medium on DX with playable fps though there are a few dips when it gets hectic.