I think Waves was trying fiat gateways and CEX.io allows you to deposit USD, EUR, GBP with your credit/debit cards. There is also the spread of ATMs and http://uphold.com/ which would be a major force in getting fiat into cryptocurrencies. Also there are things like localbitcoins and dashous. People could also ask people to pay them in cyptos.

I think the same methods would be utilized more and some banks/brokers will allow few major crypto purchases. People still have cash and they can work for crypto payments and HODL and spend the fiat they have left. So I'm not really worried. Banks will only make things harder and slower.