Even though digital assets will serve as a great alternative in the nearest future, we are going to still need banks to convert to fiat in order to cater for our needs. At the moment, digital assets are not an acceptable means of exchange universally.
It will serve as great alternative and hopefully will develop service structure around itself so it will actually be possible to live without banks, with companies like coinbase, binance and etc (working with visa, master card and other big corporations)
Banks will never be removed in our lives though I also imagine in the past that these exchanges might be the next banks and they will be eating these banks and put it under them. But as you said, this will stay as an alternative maybe more like of an asset that people hold to generate profit in the long run.
I think as time will pass bitcoin will be like gold, right now we are using it but in the future, it will be an investment, an asset that people will hold while we use other means of payment.