Personally, I think it would benefit their sales it these "optimisations" made there way the the first Crysis prior to the release of Warhead. People are taking anything they say with a bucket of salt right now with regards to performance, but thats their own fault for misleading people saying things like it'll run better on a slower quad than faster dual, etc, etc (we all know the stuff by now).
So if these optimisations actually exist, and the engine is running so much better (hell, even slightly better), it would really work in their favour to release them as a patch to the original Crysis now.
I will probably get it on release either way as I like running around the jungle, but I am not holding myh breath for performance optimisations - when the only improvement I really want from the game is better ATI/Crossfire performance...