Comment by mhuffman

For #2, imagine how fast a new Trump presidency (unlikely, I think, but you take my point) would stop shipments to Ukraine. Also a very large economic impact here (say something twice the size of 2008) might have our government at least focused on something else rather than having to explain why a bunch of citizens are homeless and hungry but we are sending billions to Ukraine every month. It is one thing to support a war across the world when it is "just money" and everyone here is mostly fat and happy. It is altogether something else when you have to start worrying about your own family at home.

As for #3 a new person taking power can bend to local sentiment to keep up pressure but without the full commitment that Putin is making in Ukraine. This could play well locally (I suspect not a lot of Russians are happy to die for Ukraine) and be more "Western friendly" than a full-on war.