The West won't intervene militarily, this will essentially be an economic war, with the West implementing sanctions and freezing Russian assets.
Putin can win this if he gets China's support, which seems quite possible since they're now very close economic partners, with their recent energy deal.
America seems very weak diplomatically, Russia is brushing Obama's and Kerry's threats aside as if the USA was a second rate power. Obama is by far the weakest president of my lifetime, Putin owned him on the Syrian crisis and it looks like this will happen again.