If the only manned missions are to the ISS it makes no sense to worry about Russkie lift dependency, since the operations are joint to the fullest degree possible in any case. Would you have Shuttle go up and evict the Russian scientists and astronauts? Any mechanism for resolving conflicts about resource, scheduling and participation will either be able to maintain things along current lines, or degenerate to the point of the ISS needing to be abandoned anyway.

I suppose there's a vague prospect of the Russians at some point saying "We're the only ones with live-cargo-rated lift capacity, so we now own the ISS. No one else is getting up there. We kept Mir running, so we can keep the ISS up there." At which point, the rest of the world has the option of stopping funding the ISS until such time as they have human-safe lift capacity, hence saving a large chunk of change for other purposes.