An idea would be to not use one blockchain but a tree of blockchains. Say one blockchain is attributed to London so that if you make a transaction in that blockchain it should be quite fast. Now you want to send money to bangkok, the transaction bubbles up and you get the idea.
edit: obviously someone got that idea before; my point was meant to be that it would be a shame to use a centralised solution like the services of private companies.
edit: obviously someone got that idea before; my point was meant to be that it would be a shame to use a centralised solution like the services of private companies.