Imagine the year 2025, when everyone has wallets with different crypto's in it: people will probably want to buy things with it in stores. The problem is that people do not want to wait half an hour for several block confirmations.

Will there ever be a world where people can pay with any cryptocurrency in a store? Will we need some kind of smaller 'buffer' wallet, that allows people to buy things instantly with a crypto paycard, so that the actual amount is taken from the address later? What about all these different cryptocurrencies; you can't ask a store to have 500 different wallets.

Just curious if there is a solution to this problem.