Ukraine is looking increasingly odd. The ousted president is on the run, his chief of staff defecting back to the new government side and getting shot at in the process. Russia is treating the new government like a crazed animal of some sort rather than rather moderate politicians. However, things are unfolding with an odd amount of calm.
There are majority-Russian parts of Ukraine, mostly towards the Russian boarder, as well as the Crimea, which was Russian until the 1950s. How those ethnic Russians react to the new government might be the key. If they are not interested in getting absorbed into Russia proper, they might be interested in some regional autonomy that keeps them well in the Ukrainian orbit. If there's enough (not a majority but enough to look like one with Russian spin) pro-Russian sentiment there, Papa Bear might come in and "protect" its kin-folk.
The Crimea might play out differently, since it has a Russian naval base there. Sevastopol might wind up getting spun off as a Russian Gitmo (not in the prison sense, but the idea of a foreign base belonging to the base's hegemon) with the rest of the Crimea staying with Ukraine, or used as a toehold for a takeover of the Crimea as a whole. Since it's a peninsula, Russia might be in good position to snag it and fortify it such that it would be fool-hearty to try and take it back.
That's just the eastern side of things; we still have a new government, headed by a wonkish Baptist pastor (Carterov? no, Turchynov) as interim president and a unwieldy coalition of reformers and crony capitalists that fell apart after the Orange Revolution. That side will wind up taking longer to play out, as new elections will shape (if outside events let them) how the new government looks.
However, events in the eastern part of the country will likely get in the way. A rather ruthless deposed president likely backed up by an even more ruthless ally has yet to be clearly heard from. Trying to pick out the likely makeup of a 2015 Kiev government assumes there is a Kiev in 2015.