After the Russian military publicized their "second phase" goal, a look at the map (from today) shows possibilities and likelihoods:
Mariupol will fall. Strategically, two questions will have to wait for an answer:
1. Will the Russians start a new offensive west along the coast toward Odessa and a landbridge with Transnistria?
2. How big of a battle for the Ukrainian Donbas salient will the Russians attempt? Options here are:
2a. the Kursk model, a two-prong attack from north and south toward Dnipro, to ultimately encircle and destroy the bulk of Ukrainian forces holding the salient.
2b. the WW I model: more or less frontal attacks along the salient trying to push the Ukrainians back, out of the Donbas as far as feasible.
Any competent general with confidence in his forces at the present force ratios would go for 2a, but I have my doubts about both Russian competence and confidence, and 2a is the kind of plan that either works or fails, while 2b is fluid and would allow Putin to declare "mission accomplished" wherever he chooses or is compelled to do so.