Russia will probably officially Crimea and be done with it unless they decide in going back to constitutional reform agreed upon on the 21th feb. Putin wants the 21th February deal respected, but that would mean the interim government would have to be considered illegit by the West, and I doubt that will happen. If they put up sanctions agaisnt Russia, they won't last long. If Ukraine decides to go to all out war they will be unprepared and we might see Russia's true military prowess (or lack thereof) for once.