While we're here, you'll have heard that Russia has announced that it
will[1] stop being part of the ISS as of 2026
and go off and build their own one, with blackjack and hookers...
Which will make it the fourth country to do so, after the USSR (albeit tailing off into the Russian Federation), the US and most recently China. But just like the US has had to reinvent the Apollo Program(me), they can't expect to just dust off the soviet-era stuff and get back to their full stride.
I can't see this being more than posturing, right now. They're upset that they've lost their monopoly on man-rated launches (we now have SpaceX, maybe Boeing coming up; and there's the Chinese, but already only for and by themselves) and I've no doubt that the non-Russians can quickly get some of the robotic supply missions (at least) to act as orbit-raisers if they disconnect the Mir-2 modules[2].
I'd say no real loss if they organise a proper de-docking from Unity. And, by their own admission, the ROS modules are on the edge of their design-life anyway so I can't see them drifing it off to act as the (initial) backbone for any neo-Mir they will have to start afresh with. It's probably going to happen
anyway, hopefully before anything fails so critically that they
can't bodge a repair in time.
(Really, there are far more physical dangers associated with human habitation in space than 'mere' political ones. Unless there's an active act of sabotage[3], I expect the end of the ISS to be pretty much a natural end of either unseen disaster or abandoned as no longer fit for purpose. Russia is no longer a necessary partner, from an engineering perspective, if diplomacy cannot keep them on board.)
[1] Well, by their rhetoric. It's going to be either an empty threat or a costly one.
[2] Zarya: Now mainly storage; Zvezda: Living/propulsion; (Pirs, then) Poisk: Russian EVA facilities; Rassvet: Cargo space/docking; Nauka: Russian laboratory; Prichal: General docking; ...all pretty much duplicated (or derussified) in every facette other than propulsion with the US/Other-nation modules and nodes, which also does the heavy lifting in the Power department.
[3] Which is probably less likely than when there are 'competing' space-habitats and some 'accidental' ASAT-like action is made upon the opposition by one or other or both beligerant parties.