I think large-scale nuclear war is more probable DURING the conflict than at the end or after the outcome is known.  And I think it's more likely to be a mistake or failed control system (human, not electronic) than an intentional act by any leader.  

Specifically, I don't believe that any outcome is particularly more or less dangerous on that front - the Russian instability is pretty much locked in regardless.  As such, we should hope for "Russia goes home with zero gains" as the outcome that gives the least incentive for future incursions.