I just can't see it NOT being a FIAT vacuum cleaner.
Don't worry, I don't think Bitcoin will ever be a "fiat vacum cleaner". Think of it this way....
There are 2 general types of "money" needed by advanced economies. 1 type that keeps prices stable (for trading) and one type that keeps the supply fixed (for store of value). The one that keeps prices stable is simply a way to denominate trades - it isn't actually "money" in the sense of being a bearer token like commodities, precious metals or cryptocurrencies. On many websites now you can even choose how to denominate your trade - Canadian Dollars, $USD, EUR, whatever.
Those trading currencies need to have a variable supply - like the USD. A fractional reserve system which inflates and contracts according to liquidity requirements. If you don't have that and use a fixed supply currency like Bitcoin for trading then half the businesses in the world will go bust and the other half will make supernormal profits which are not sustainable.
So I don't see bitcoin ever being used as a trading currency en masse. (You don't see prices ever being denominated in gold and neither did we when there was a gold standard). Bitcoin is a base asset which can be used to "back" trading currencies for example or facilitate the capitalisation of whatever markets, but I think prices will still continue to be denominated in prevailing regional currencies.
