So, if all the banks in the USA, due to some regulatory act, decided to include Bitcoin in their financial platform and everybody started using it at once, would bitcoin be robust enough to handle that traffic?
Do you seriously think that this is going to occur?
Even if you increase the block size to 200MB it wouldn't be enough to handle all the txs in the USA (little own the rest of the world).
(so your scenario is not only somewhat ridiculous but practically not able to be handled by Bitcoin at all)
(and although I'm guessing you have no idea about it - the time taken to verify all the ECDSA signatures in said super-sized blocks would actually be more than 10 minutes)