"The almighty dollar" has been adopted into economies (with greater or lesser officiality) all over the place, in parallel with or instead of a less reliable local alternative.
In subtly different ways, Bonaire, British Virgin Islands, East Timor, Ecador, El Salvador, the Marshall Islands, Micronesia (x6 nations, technically, federated), Pallau, Panama, Turks-and-Caicos and Zimbabwe, if I'm up-to-date on all that, make their use of the US$ for their own reasons (and two of those territories are British Oversees Territories). Not counting the various external US territories themselves (like I wouldn't count Falklands or Gibraltar as odd places to use GB£s).
There's a degree of "too big to fail", to these choices. Which isn't necessarily a perpetual given. (A greater chance of the Dollar failing would probably change the minds of those that currently support it and thus provoke it, but so far it's been manhandled over such things, or been seen as not as vulnerable or awkward as the alternatives. So far.)
For Argentina to 'join the dollar' (and have no real control over the process) would not be totally extraordinary. But it'll not be easy or simple, either. I'd put some money on it not actually happening, if I actually had some AR$ to wager[1]. Expect reality to hit the new president fairly quickly. The kind of thing for which a 'populist war' might have to be started, to distract people with, unfortunately. Something small, of course...
[1] One way or another, it'd be the best use of my pesos...