Whom in whose right mind would want a war? putin! (exclamation point)
Putin doesn't want a war. And it's a moot point because there isn't going to be one. Vladimir Putin is the most powerful man in the world right now (a position previously held by every U.S. President since 1945). He's going to get what he wants.
He'll continue to support the separatists, while denying it and the West will continue to issue toothless sanctions that don't affect their ability to buy much-needed Russian oil.
Eventually the fighting will stop. Western Ukrainians are already getting war-weary, tired of being told their sons are fine despite not receiving letters or phone calls in weeks. Ukraine will split in two with Donetsk the new capitol of Novorussiya. If Putin plays his cards right, he'll have a pro-Kremlin government in Kiev as well.
The West has no appetite for all-out war with Russia.