do you think the US or any other country will get rid of cash and coins in favor of a system of credits?

I think in time, as computers get more efficient and smaller, so that they are smaller than a credit card, then this will happen. It seems strange to us and maybe even a little bit scary, but that's probably what people with bags of silver and gold thought about paper money in the past.

Not in the foreseeable future. There will always be the working poor, who don't have bank accounts, and the informal economy that operates on a cash-only basis...

I hope not