My hypothesis is that Ukraine will experience huge military losses so more foreign volunteers and intergovernmental military and peacekeeping alliances will come to its rescue. This move will push back the rebels, while Russia will increase direct participation in the war. However, its economy will face the consequences and Putin may well lose the trust of his avid supports. Both parties will then call for a ceasefire and they will try to agree to a peace treaty of some sorts.
Not likely. Even if Russia was to send it's army into Ukraine, no Western nations will intervene. Why? Russia is desperate. Their economy is in shambles. They have nothing to lose and are desperate to start a war so they can balance the scales should they emerge victorious. But Western leaders are smart enough and will avoid swallowing the bait.If Russia continues to push forward, foreign powers will have no choice but to intervene and continue with sanctions and, at some crucial point, more drastic measure.