The only way I can see your comment being correct is if you're open to redefinitions of “blockchain” which do not require either immutability or the global public ledger. The current blockchains handle a vanishingly-small fraction of global financial traffic using far more equipment, data, and power — there's no magic wand which can allow you to scale up by many orders of magnitude without architectural changes.

That could be solved by splitting into local blockchains so the global network only handles transactions between local banks but that seems like it's basically giving up most of the benefits claimed in blockchain marketing.