Indeed the Orange Revolution parties had a majority before Yanukovych had one.

The question is if Putin really wants to go all-in.

A not much discussed but IMHO pretty interesting aspect of the Crimea invasion is that no shots have been fired by Russian soldiers (at least on target). One possible motivation is that this is the level where Putin wants to stave off further escalation (which, after all, might go on until WWIII). Another is that he does care about perceptions, even if not that of the West but that of the local population and the home crowd. The latter is supported by how the coup in the Crimean parliament was engineered, which doesn't look like something improvised, but like the execution of a long-prepared contingency plan designed to give the appearance of democratic legitimacy at every step.

_{*Lunatic*, n.
One whose delusions are out of fashion.}