If the war had gone well for Russia in Ukraine, they would have been emboldened regarding their (explicit) plans to “reclaim” territory that is now in the EU and NATO. Europe’s original plan was to watch with horror as Ukraine fell in a matter of days. Russia would then reasonably assume there might be a weak response if they attacked the Baltics, for example.

No, I don’t think the West would be as secure in a world where Russia’s imperialist risk-taking paid off vs a world where it is being bled dry and hamstrung in some of the most humiliating circumstances imaginable.

This whole invasion was demented so I doubt we would have been secure. Why would Russia not attempt to "fix" their Transnistria-Moldova historical problem after? Or support Serbia and interfere more in balcans after, especially with full manouverabilty on black sea? Have you seen what they were proposing Viktor Orban and nationalist Hungarians for Carpathians/Transilvanian area and Western Ukraine? If they agreed to something like that we would have to kick them out of EU... All this within the immediate geographic vicinity and reach post conquest of Ukraine, I am not even talking Nordics and NATO or Baltics or the border issues already happening with Poland/Bielorus.

Nah, this Russia is not a good faith actor, and needs to be exterminated in the battlefield with anything short of nukes for the good of the West and ultimately the world.

I guess that depends on if you consider Estonia, Lithuania, Latvia, and Moldova as part of Europe, because if Ukraine fell, they'd be the next targets, except then Putin (or his replacement) would be pulling reserves from Ukraine as well.