I highly appreciate your fierce enthusiasm but nobody will come back to the ruined countries. No one below at least regional level oligarchy. The oligarchy will only consolidate and strengthen. They will bring in new people to replace the former native population, don't worry. Nationalism was only a poison intended for the (former) native population, its job is done. Russia will survive, Ukraine maybe will. Poland is not even at war and follows the same pattern - emigrants replaced by imported population, skyrocketing wealth inequalities.