You again come up with mutually exclusive starting conditions
There is no good medium of exchange on par with fiat currency that would be at the same time as good a long-term store of value. Basically, you have just invented a perfect money, instantiated it (which you can't), and then pitted it against a real fiat currency that is always inflationary and thus can't be a good long-term store of value. Indeed, the fiat currency would lose and collapse, but this approach is meaningless as one can always imagine something perfect, not possible in real life, and ignore this fact
What’s the problem?
All your reasoning about Bitcoin taking over fiat can be reduced to and is essentially a tautology, like A is better than B because A is better than B
Simply put USD against the national currency of any shithole country and USD will surpass the latter in any aspect.
Bitcoin itself could be such a currency, had we solved all technical issues
It is not a technical issue
You can't solve the internal inconsistency between money functions. Put differently, you can create a good store of value (e.g. gold) and you can create a good medium of exchange (e.g. the American dollar). You can even create a so-so currency somewhere in between. But you can't create a currency which would outshine everything both as a good store of value and a good means of exchange. You can only hypothesize about this kind money