Russian intervention in Syria

When the Russians started moving equipment to Syria my first instinct was that they were going to help Assad survive. Claiming to 'fight terrorism' they would just be pulling an 'Erdogan.' Nusra an Ahrar al-Sham would be the targets.
No way were they going to attack IS.

But now I start to wonder if Putin has a grander plan. 
What I would like to know first is whose initiative this Russian intervention was. 

Putin's initiative? Worried about his embattled ally, or about his mediterranean navy base? Looking for a bigger strategic involvement in the Middle East? Worried about losing influence over Assad to the Iranians?

Iran's initiative? Running out of options to save Assad's regime. Asked the Russians to pitch in. 
According to the Financial Times Tehran was 'surprised' by the Russian intervention but its story is based on a unnamed source and since a lot of the Russian equipment used Iranian airspace to go to Syria I don't think we should take it too seriously.

Assad's initiative? Worried, like Abadi in Iraq, about growing Iranian influence over his regime. Iranians building a parallel power structure with militias like they did in Lebanon and Iraq. Invited the Russians as a counterweight for that.

I don't think we'll get an answer to that question any time soon. The only thing we can do is monitor every move for clues.

Russian troops are reportedly stationed no where near IS front lines. Having a lot of people concluding that IS is not the target. But that doesn't have to be the case. Ground troops are just a small contingent of the Russian force so far. Not enough to conduct any offensive. Russian action will come from the air component. Their position is irrelevant to where they will strike.

What I did see was Russian drone footage from Palmyra. Now this could be a case of maskirovka. Trying to fool us that IS is the target. I actually joked last week that Putin could pull a nice PR stunt if he would 'liberate' the antiquities of Palmyra. But it could also mean Putin actually wants to degrade IS, and maybe try to succeed where the U.S. have so far failed, to create a strong strategical and diplomatic position in the Middle East. 

With IS out of the way Putin could offer a political solution for Syria without Assad since the West biggest fear has always been that toppling Assad would empower IS. Cease fires with the opposition are already being negotiated, like in Zabadani. 

Rouhani has been hinting at a political solution, but only after the fighting stops. Big question is whether Syria is in Rouhani's jurisdiction. Up till now it has been Soleimani's domain, under direct guidance from Khamenei. Is Rouhani operating on his own, part of the internal Iranian struggle between moderates and hardliners? Or is Khamenei playing a good cop, bad cop game through Rouhani and Soleimani?

Another possible, but cynical, scenario is the one where the Russians destroy Nusra and the moderate opposition. Making the Syria conflict just one between Assad and IS. Forcing the rest of the world to support Assad.

The big if is whether a hand full of Russian planes could make such an impact. That remains very much to be seen.