Nonsense, NATO didn’t exist in 1941 if a NATO country for example one of the Baltic states is attacked, the principle of collective defence which is enshrined in Article 5 of the Washington Treaty is invoked.
Article 5 provides that if a NATO Ally is the victim of an armed attack, each and every other member of the Alliance will consider this act of violence as an armed attack against all members and will take the actions it deems necessary to assist the Ally attacked.
Putin won’t touch a NATO country. This is about gaining control of the Black Sea and creating a ground bridge around the Black Sea to Moldova. It’s part of China’s silk road plan.
All I can think about in all this is the two apes from the region living in Tipp who both laughed at the possibility of war in Ukraine - the Ukrainian piano teacher in Cashel who was so confident she put her face on the front of the local paper and @carryharrys mate from Lithuania living in Cahir or wherever who also belly ached with laughter at the thought of this.
Which does not invalidate the point you raised on a guerrilla war. He is going to be bogged down here. There has been Kremlin supporting leadership in the Ukraine on and off since the break up of the Soviet Union. Twice mass protests brought those regimes down. In order for him to effectively control the Ukraine, he needs a regime he can trust and permanent military oversight. There is clearly going to he a long and sustained Russian presence there.
Trying to make predictions on Putin is pointless, let’s quit before we make any more rash statements.