I doubt that another fiat currency will replace the dollar, not even the yuan. So, it will most likely be a basket of currencies. At the same time, it's not like the world actually needs a single reserve currency, and it might be better off without one.
The other day, I watched a Keiser Report, on which the guest asserted that bitcoin is the most likely candidate to become the next global reserve currency. That makes complete sense.
Could be basket containing USD, EUR, CNY and JPY...
This really answers the question. I think Bitcoin will be the next big thing in the nearest future. Onwards!
There's a good possibility that BTC might be the reserve currency.
Gold and silver will continue to be a store of wealth. But, in terms of currency, cryptos in general and Bitcoin in particular seem to be the best option.