After NASA canceled the shuttle program, the Russians and their Soyuz were the only means of manned travel to and from the station for years. I don't know how the Ukraine war has impacted that working relationship, or to what degree it pushed NASA to contract work out to these shitty fucking companies. But if it comes down to it, I'm sure something will be arranged for American astronauts to come home via Baikonur as they've done so many times before.