I'm too lazy to actually sift through this protocol change proposal... but I don't see how it's possible to do this. I mean possible at all: the whole idea behind Bitcoin is that the entire transaction history is available for public verification in the blockchain. Every transaction ever made. Remove that, and you're trusting a central authority to keep their records straight: that places all the power in their hands, and that's one of the things Bitcoin is specifically designed to avoid.Again, I haven't looked at the specification or anything, but I don't see how it could possibly work.