When the military forces refuse to attack their own fellow citizens, then in normal circumstances you'd expect a successful coup d'etat. Unfortunately, in this case Putin will send in his own military who are unlikely to back away.
It is a brave and decent stance by the Ukrainian military to refuse to participate and definitely a 'score' on the side of the protesters.
If Yanukovych fails to maintain his grip then the best he can look forward to would be asylum in Russia; but more likely death or a very long term of imprisonment so it is completely understandable that he will do all he can to avoid such personal catastrophe.
Add to this the importance to the balance of power that Ukraine remain loyal to Russia, then this battle does not give much chance to a resolution without a great deal of violence.
The US wants to destroy the last vestiges of Russian military might to ensure complete hegemony. China will not stand for this unilateral rogue element in the world, so it leaves you sitting in a very dangerous situation with the bells of war at your doorstep. Such a war could escalate very quickly affecting much of the world.
