Between the propaganda on state TV, and general belief in Putin by half the nation still today...things could marginally continue on.
I would say this...at the pace of advancement, at some point, I believe the Ukrainians will corner 10,000 Russian troops in a pocket and take the mass group as prisoners. That might be enough for the pro-Putin crowd to question the state-TV message.
Sanctions-wise, there’s elements of the economy lessening. They grow their own food and shouldn’t have to worry about that.
another factor is that soon the weather will deteriorate into fall rains and mud, then winter. In the absence of logistical support, the Russians may lose a lot more than 10,000
Once Putin is gone, the successor can safe face and withdraw.
And then remove the sanctions.