Cryptocurrency continues to gain more ground but I still have my reservations about it being the currency of the future. If by design, cryptocurrency has a finite volume of transferrable currency, do early adopters have an unfair advantage that could potentially make the currency unusable? I don’t see how it could possibly be fair when earlier mining yielded currency more quickly.
Fiat currencies will probably always exist. Digital crypto assets like Bitcoin or Ethereum will exist alongside them. Bitcoin can be an asset like gold, of which users keep a portion of their networth to protect from economic uncertainty. Its deflationary policy may make it less usable as a currency, but at least crypto gives people choice.
In terms of facilitating payments, cryptocurrencies are worse in almost every way I can think of compared to existing systems. They are (currently) slow, have high transaction fees, but most importantly the non-refundability of crypto transactions is a bug, not the feature crypto proponents suggest.
However, as a store of value (e.g. "digital gold"), I think crypto has real potential. There is a reason crypto is very popular in places with hyper-inflationary monetary systems like Venezuela and Iran. And compared to actual, physical gold, crypto is almost better in every way: it is much more easily transferred and stored, and the ledger means establishing "provenance" is not an issue. Yes, it's obviously currently extremely volatile, but it's not hard to imagine that volatility lessening over time.