Between 1790 and 1920, every monarchy said democracy and republics were failures and paths to dictatorship, until all the monarchies collapsed or were reformed into bourgeois democracies. I think by 2047 something very similar will happen with bourgeois democracies and communism.
I think these river boundaries from Kherson to the Oskil are the goal for as long as Ukraine is putting up a fight. With drones and surveillance, offensives are back to the WW1 era. I don’t think they’d plan major offensives until Ukraine is in full collapse mode. It’s not worth the manpower in deaths or in occupation.