I assume that Rostov (and other such cities rebuilt after 4/10) have the same vibe as cities like Chandigarh, Islamabad, Brasilia, or Abuja have IOTL? And on that note, I assume the few surviving people still living in the former Uralic republics are near-100% rural ethnic Russians who refused to leave.
Right after the war, you'd probably get a renaissance of commieblocks, except they'd be even more shoddily built than the old ones, while later on you'd probably get some modernist planned cities, but it's also possible that, in order to raise morale and try to regain something of what was lost, you might see cities being rebuilt in a much more traditional style, with an eye to modernity - with streets being drawn for pedestrian and public transport traffic rather than cars and tanks, and modern renewable energy solutions incorporated in buildings that look like they could've been built during the Tsarist era.