We don’t have a medium of exchange or unit of account problem. The dollar does a pretty good job
We have a SOV problem. Well we had one.
Discussion
If it becomes a store for more value, the dollar won't be a good unit of account any longer.
Medium of exchange matters if you can't exchange your other MoE for Bitcoin easily and securely/reliably.
It will become UoA by default once other currencies fail, or by proxy if it starts being used to collateralize other currencies.