Well, I just explained to you the cases that Russia would and wouldn't intervene. Collective Security Treaty Organization mandates that Russia intervene on behalf of Armenia if Armenia is targeted. I don't see a reason for Russia to violate this, because Russia basically wrote the charter itself. On top of that, MASSIVE drills were conducted last year (under the name of "Interaction") in Armenia that included Russia and other CSTO nations.
Why do you think Azerbaijan has yet to attack Karabakh? Aliyev pretty much reminds the world that his country's defense budget is larger than Armenia's state budget everytime he is in front of a microphone. Two reasons: either Armenia has weaponry provided by Russia that is publicly undisclosed but realized by Azerbaijan and/or 2. Russia has made some indication to Azerbaijan behind closed doors that they are not to initiate conflict.