I mean, when I look at urban warfare, I think of the following possible outcomes:
1. Total annihilation, e.g. Warsaw at the end of WWII.
2. Splitting the city up into factional neighborhoods. Possible but given the situation in Kiev, there don't seem to be many Russian supporters there anong the native population (this is not true in Eastern Ukrainian cities)
3. Subduing the defenders and installing a puppet government. I think the best model here appears to be the Soviet Union crushing the 1956 Hungarian Revolution.
#3 seems like the most obvious intention of Putin, but I just don't really see how that is possible in modern Kyiv. In 1956 Budapest there were plenty of Communist supporters - indeed, they were the ones in power before the revolution.
The "best" outcome I can see from this war is that Putin completes the annexation of Luhansk and Donetsk, with possibly some other eastern regions e.g. a full land bridge from Crimea to Donetsk, as well as Kharkiv, but I just don't understand the attack on all of Ukraine. If anything you'll just get a further sorting of the country where everyone who despises Russia moves to the west and everyone else decides to stay/move to Russian-occupied areas.