Wii U and 3DS already solved this problem without any need for full game installs. Patches contain only the delta, and files in the patch can supersede files on the disc/cartridge.
Sure, but then you have to manufacture and build a version of the game specifically to meet those criteria rather than port equitably across multiple formats. I suppose in theory that could mean a better version, with faster read speeds, but it still creates dev barriers that aren't consumer-friendly either.
And again, this is 100% imagination at this point. I think they'll go optical.