Syria is almost entirely back under government control, what does that mean? Whilst Russia has been the main player in supporting Assad from the air, without Iran there would be no Assad. Iran is the real political power in Syria
What could this lead to? Iran’s intention is to destabilize the arab world as much as possible and put pressure on Israel. Now, with its access to the border with Jordan, there is a real possibility it will begin work to create chaos in Jordan. There are two objectives, if Jordan can be destabilized enough, it will raise alarm in Israel for the security of its border. In Syria, Israel has the buffer zone of the Golan Heights in Syria to keep Iranian proxies such as Hezbollah at arms length. If Jordan were to become unstable, there would be no buffer zone.
Secondly, if Iran through Syria can unbalance Jordan, then it would also have access to the border with Saudi Arabia, and this I think would be the main objective. Ultimately Iran wants to see the collapse of Saudi Arabia ,its nemesis . Slowly but surely Iran is surrounding the country. It has strong influence in Iraq so therefore has access to the eastern border, Yemen on the southern border is a war zone and Iran supports the Houthi rebels there. The next logical step is to create chaos in Jordan and give Iran access to the northern border of Saudi Arabia.
Russia isn’t strong enough to control Iranian influence in Syria and I’m not sure it would be unhappy if Iran were able to destabilize Jordan an American ally. Jordan in many ways is a fragile country. It is small and poor with hotbeds of potential unrest waiting to explode given the opportunity. The cities of Zarqa in the north and Ma’an in the south are pretty much no go areas, the army and police have to stay out of those cities and manage them by controlling the roads in and out. Given the opportunity, they would rise up now if they could. If Iran, now with its access to the Jordanian border can create enough chaos, it is certain fighting would start in Jordan. This is a huge security concern for both Israel and Saudi Arabia.
The point is this, the war in Syria stopped being about revolution a long time ago. Today it is about increasing power in the region, having geography and the strategic upper hand on your side. Iran is playing a long game here. Winning Syria is just one step further towards its goal of being the dominant power in the middle east.