Turkey controls the Bosporus Straits. Since the days of Peter the Great at least, Russia has sought warm water seaports and access to the Mediterranean Sea. The Crimean War was fought to restrain Russian access to those straits. Turkey is preventing additional Russian warships from joining the Black Sea fleet. If Turkey leaves NATO, they can let the Russian Navy full access to the Black Sea, which is Ukraine’s underbelly. Turkey adds more to NATO than Sweden and Finland would. Replacing an asset with a liability is never a good idea.
True.
Can't kick Turkey out anyway, but an the alternative could be a parallel multilateral alliance including all or most of NATO other than Turkey. Just slap a different label on it.