If everyone in the world gets into crypto and cryptocurrency will become an official global currency, do you think bitcoin then will stop depending on fiat currency? Or will it just co-exist with fiat?
I would say no.
We are still buying and exchanging cryptos using currencies. Americans use US Dollars; Europeans use Euros to buy bitcoin, ETH, etc.
They are always together and depending on each other.
Also the stock market could also affect the crypto market in some ways if you pay attention.