Timothy Snyder has written a good analysis of the current situation in Ukraine:
A Way Out for Ukraine?
One more important aspect should be taken into account too: the Ukrainian civil society which started the protests and is currently growing in strength. Non-partisan protesters on streets are very sceptical about the opposition, and demand a complete overhaul of the political system. A deal that could possibly be struck between the political elites will surely be not enough for them. The opposition understands and is concerned about this because hundreds of thousands of non-partisan protesters are the opposition's only resource of power. If the civil society sees that the opposition is using them for bargaining, it will withdraw its support, and even if the political elites strike some deal, the protests will likely to continue.
The power of the non-partisan protests is indeed amazing, and we can witness fantastic examples of self-organisation via social networking websites and offline. It's almost a perfect case of horizontal forms of organisation and leaderless resistance.
(The _uncivil_ society [first and foremost, the extra-parliamentary extreme right] is problematic too. It is, fortunately, not as strong as the civil society, but it is already causing serious problems.)
Even if the protesters are ready to support the opposition at early or regular elections, the civil society needs guarantees that it will have a strong say in the process of Ukraine's development after the opposition - sooner or later - takes power. This can be done through clear and unambiguous promises of power decentralisation, re-establishing of parliamentary democracy, establishing of social councils, strengthening of the NGOs and trade unions, etc.