If that was the case, I'm not sure how they'd achieve a complete turn around. The Russian public have been subject to ludicrous propaganda for such a long period, they can't just flick a switch and change everyone's minds. They may well ease away but I doubt it'll be that swift. It's not like the sanctions will ease. Ukraine would be after reparations, there's all sorts they'd need to explain and in a way that whoever does take over wouldn't themselves be implicated. Because of what they've done in Ukraine and what they've told the Russian public they can't just go "Thats it we're leaving." The are tens of thousands of families (at least) without their fathers or sons, to be then told their sacrifice was based on a lie and utterly futile is another thing they'd have to try and sell.
It just wouldn't be that easy.