On that part we agree.
On whether there would be a sustained and effective insurgency in the East, we do not.
Putin’s stupid thugs thought that Eastern Ukraine would all support them but it didn’t happen. It won’t happen if Russians invade either. The Russians will be sitting ducks just like the “Ukrainian rebels” have been. They will be encircled in the cities, starved out and sieged. Then they will run back to Russia with their tails between their legs, just like Comrade Strelkov, and just like the Red Army fled Afghanistan in humiliation and defeat.