I think that we can assume that all the fiat money will be going into crypto.
Let's be realistic here.
Even me myself as a person that definitely wants bitcoin or crypto in general to succeed bigtime, assuming that all fiat money will be going in to crypto is sort of wishful thinking in my opinion. I don't think you cant have everything in crypto as long as there is poverty. Some people on 3rd world countries cant even afford mobile phones, how are they going to transact?
Though it's possible that in the far future every currency will be digital, I highly doubt
everything will be decentralized(though possible); as much as we'd want that, I don't think the government will allow that.