Russia/Russian oligarchs aren’t going to torpedo the Russian economy. No way. Economic isolation would wreck Russia, and the oligarchs would yank Putin before that happened. Sure, Putin wants Eastern Ukraine, and will probably try to angle things so that it becomes a failed state, but he can’t acquire Western Ukraine.
Beyond those, no way. Moldava will probably try to have a referendum, and if no Russian troops are within its borders, and the referendum passes, that (after E. Ukraine) will probably be the end of Putin’s goals.
That is the Eastern Europe we will probably end up with, sadly, but that is what you get with an incompetent president, a Sec. of State that gives the word bumbling a bad name, $17 trillion dollars in debt, and an American populace that is sick of endless wars.
“Economic isolation” basically translates into Europe not buying gas & oil from Russia. Everything else is relatively inconsequential. But by the time Europe can actually do that - IF they have the will to do so - Russia will be selling instead to China & East Asia, and likely getting an even better price.
As for Moldava, only the Transnistria region is interested in going Russian, and, there are (and have been for years) Russian troops already there, which the UN considers illegal.