Obama would be a blue ribbon idiot to start an open war with Russia. I think even he knows that. Although he may want to muddy the relations up a bit before he leaves, especially if Trump wins. This would be Obama’s version of ransacking the White House on his last night as president, and leaving a smoking, stinking mess for someone else to mop up. His hope being, that the following president will be so encumbered by all the loose ends and frayed edges of diplomacy, that their first term will be disasterous for at least the first two years.
So disasterous, that aides would be calling Obama back to the White House for advice on how to resolve it. ‘Ya’ll still need me, don’tcha?”
I believe that Putin will acknowledge that Donald Trump will be a different kind of leader than the homo 0bama or Hillary. We’ll be just find - and fences will be mended quickly.