I don't know what thisd solve. If I did, I'd help to create one but I imagine the fees for such thing would be really high too and we already have binance and a few other sites who seem to be trying to do this (6% on eur and usd, 1% on btc etc)...
I can agree to that, if a physical world where bitcoin / crypto are being use as main payment process.
Let alone the bank to work with institutional financial system and let crypto to work in the otherside, they can co-exist just allow the functions to work without any problem, bitcoin survives and keeps on moving forward no need to have a centralized institutions like banking system.