That's why bitcoin has implemented ultra-prune. Problem solved. Besides, bitcoin won't be used by all 7 billion, just like the USD isn't even used by all 7 billion.
As for the pack of gum- the whole point is to store every transaction. If you don't then there's no point anyway. Bitcoin will handle it just fine.
One option is centralization. Essentially instead of using bitcoin clients ourselves we would all have accounts with banking institutions that store huge amounts of bitcoin and when we make a transaction between two banks it would be recorded off blockchain. The blockchain in this scenario would be used like a clearing house to clear debts between these banking institutions once they become large enough. This could work but i dont think i need to point out the drawbacks.
Alternatively we could embrace multiple blockchains. This would maintain that precious decentralization at the cost of de-homoginization. In my mind the recent ddos attacks on mtgox demonstrate that decentralization is more important than homogeneity and so in my mind multiple blockchains is the better of the two options.
now if we accept for the sake of discussion that multiple blockchains are infact the better option than i say why not simply make carbon copies of bitcoin as it becomes necessary to do so? Sure some might argue, why not atleast ATTEMPT to innovate but attempting to innovate for the sake of it and not because you have a legitimately great idea on how to improve bitcoin (yes im talking about all existing alt coins) than really you are just opening yourself up to a world of possible bugs and problems for very little advantage. Not only that but you need a separate development team for each blockchain. Bitcoin is familiar it, it has been vetted, it works great, i say dont mess with a good thing unless you have a really good reason to do so, which i don't see as being the case.
So what do you guys think? I know this may sound like a bit of a false dichotomy fallacy because there are some other proposals out there such as chaum banks but again the centralization opens them up to attack. I have not yet seen any other way to solve the scalability problem with out resorting to centralization other than multiple blockchains. If it is the case that multiple blockchains is the best solution than do you guys see any reason why the second and third blockchain shouldnt be carbon copies? atleast until someone thinks of some way to legitimately improve upon bitcoin.