.
No need to worry about what they'll call it, as there'll never be money on Mars... because humans will never establish there. Or are we working on an RI sci-fi narrative?
Re: Bitcoin. Don't look now, but it's currently on an upswing, pushing $12k per coin as a hedge against growing volatility and corresponding lack of faith/trust in FIAT currency (see the recent rise in value of precious metals - same sentiment). The last high point of Bitcoin was about $20k back in 2017. Let's see if it touches it again, if at all, before we scoff. Money's being made as we type.
What you or I think of precious metals or Bitcoin as a legit store of value/exchange is irrelevant. It's all about consensus perception and confidence in a given currency.
The question then becomes: who (or which entities) are largely responsible for managing/shaping such perceptions?
Also: we shouldn't assume a move to digital currency isn't part of longer-term plans. Far easier to control transactions. Far less opportunity for 'under the table' transactions, at least when it comes to business, when there's an electronic ledger involved each time a transaction occurs.
As it is, the majority of transactions today, regardless of currency, are performed via highly traceable credit/debit cards, but there remains the option to conduct business, or at least more
discrete business, in cash, which is more tedious to trace (or otherwise, easier to launder).
If the objective is more control of a populace, the move away from cash is inevitable. With digital currency, not only can transactions be far more readily traceable, but accounts can also be seized/frozen more easily as well, particularly if cash as a reserve/backup option is no longer viable.
An extreme take, perhaps. 2020 may be the first step towards this future. Destabilization and economic collapse -- a cleansing process -- clearing way for phase II: the new totalitarian frontier.
But back to Mars. I've a suggestion for the face of the Martian $100 bill: