They need to make a replacement becqause the alternative is to wait until SHA256 isn't good enough.
I don't reall understand what are you trying to say, Man From The Future. SHA256 is just 1 of the 4 hashing functions that are used in the SHA-2 hashing algorithm!
It's possible, yes, but it's going to be a mess and require lots of cooperation.
So, better sooner than later because if later the mess will be bigger!