Russia stops at Zaporishia and Dniepro (and Donetsk) if Ukraine wants to keep losing. Kherson, Odessa, Karkiv if Ukraine really insists. They have other territories they are willing to trade to facilitate important liberations without having to destroy what they liberate. At any rate, the pace of Russian advance has increased in last year, and increased again in last months. It is far higher than the 3.5 year average of the SMO.