Not really. Under ten billion would be plenty if used efficiently. A significant fraction of addresses we want to be private, and not directly routable. Sure

Not really. Under ten billion would be plenty if used efficiently. A significant fraction of addresses we want to be private, and not directly routable. Sure, if you want your refrigerator, oven, and dishwasher publicly addressable on the internet it isn't enough, but you don't actually want that. Further, 64 bits is many orders of magnitude overkill already. So what does 128 bring to the party, besides making addresses harder to type? Also, random with a prefix is not really random.