Isn't this a great opportunity for Russia and Iran to conquer the Persian Gulf? All of the oil rich areas of the Gulf states are populated by oppressed shia arabs that could support an invasion. Russia now also seems to be allied also with the ambitious Islamic tyrant of Turkey, and with Egypt, controlling both the Bosporus and Suez. Russia is in desperate need of increased oil prices, and that is of course the only source of income for Iran too. Saudi broke its oil delivery deal with Egypt the other day, being unhappy of Egypt not participating in the failed war in Yemen. Egypt is rumored to offer Russia a naval base at the Mediterranean and Russian air born troops recently held an exercise in Egypt.
Saudi Arabia spends more on the military than Russia and has very modern weapons, but corruption and incompetence makes them completely inefficient, as their failed war against utterly poor Yemen with 50+ years old weapons proves. Iran, Turkey and Egypt all have huge armies, albeit not much in the way of the most modern equipment. Russia's navy, air force, elite troops and military competence should be a great complement.
Trump is definitely no friend of Saudi Arabia and will never enter a war because of them. The US has no interests in the region, other than Israel. With Trump's promised energy policy the US will become a net oil and gas exporter already next year and would benefit from higher oil prices. Obama doesn't want to go to history as having started world war three, and any substantial US military mobilization in the region will anyway not be ready until Trump takes office January 20th. I don't think it is a coincidence that the Russian Atlantic fleet arrived in Eastern Mediterranean on the election day. I think Putin considers taking advantage of this unique option. The war could be over within weeks and the gains would be enormous.
Besides the huge profits from controlling the world oil prices, Putin would become the greatest hero in Russian history since Peter I. The over 400 years old Russian goal of getting access to the seas in the south would come true, via its allies Iran, Egypt, Turkey. I think one needs to think a bit larger than bombing small rebel groups in Syria. That can't be anything but a pretext for making real gains.
While at it he could conquer Sweden in an afternoon too. Since Sweden doesn't have any defense and no alliances, not a single Russian soldier risks getting wounded and the conflict would not risk any escalation. With Sweden occupied the Baltic states are surrounded, total domination of the Baltic Sea and air bases would have all of Western Europe within easy reach. Even threatening a landing in the UK any day from North Sea naval bases. Sweden is very easy for Russia to defend thanks to it being a peninsula. Since Sweden can be conquered without a single shot fired, it will not be perceived as a war. The Swedish prime minister will be forced to publicly welcome this new voluntary union for "peace, independence, gender equality and responsible climate policy".