Common arguments refuting Bitcoin usually talk about how certain features make it bad currency.
(If you’d like to get into such arguments in detail, I recommend Noah’s post here. If you’d like a counterargument, do consider reading my post here.)
However, a Bitcoin future doesn’t necessitate Bitcoin being used as everyday currency. In a Bitcoin future, you could still be paying for your coffee using your local currency. Americans might still be buying coffee in USD; Singaporeans might still be purchasing chicken rice in SGD.
See, a Bitcoin future might simply entail Bitcoin being the reserve currency. Similar to how currencies are generally measured upon the USD today (hence making the USD the reserve currency), currencies might be measured upon bitcoins in the future.
And just like how the USD isn’t therefore automatically used in every single country today, bitcoins won’t be used for everyday transactions in the future, either.
(Many of Bitcoin’s critics seem to gloss over the above types of possibilities. In critiquing Bitcoin, many immediate arguments make the assumption that a Bitcoin future equals everyone buying and selling in bitcoins… which is, I think, both unrealistic and overly simplified.)
You can find me on Twitter @ramwithouthorns.
Another obvious use case is BTC as a settlement layer, which is already happening with the Lightning Network