I think we'd need to invoke article 5 to stop Poland from rolling up on Russia in that case.

With the current hard-line politics and that absolute hate between the two, there is a hair trigger on that escalation.

100% that NATO invokes article 5 because of fallout landing on the first square centimetre of Polish land, or wherever. Then the big guns, big tanks, all conventional, come out, and the Russian oligarchs and Silovikis are left with two choices: MAD and lose all their accumulated wealth and comfort, or negotiated de-fanging.

> ≈ 0% that the West will retaliate.

Putin had hoped for that after 2014,but he was in for a nasty surprise in 2022. The probability of NATO to strike back is 100%. It doesn't matter if they destroy the Black Sea fleet or naval bases or do something else, they already communicated to Putin several times that the response will not need to be nuclear but for sure will be painful.