What Happens in Homs Will Not Stay in Homs
The impending battle for the war ravaged city might determine the fate of large swathes of the Middle East for generations
If the reports that Assad's forces have retreated from Hama, handing it to the rebels, are true, they will be retreating to mount a last stand at Homs.
If the rebels capture the Homs area, it is all over for Assad. His Alawite coastal heartland and all the ports (circled in pink) will be cut off from the capital Damascus. Iran would lose access to all but two border crossings into Lebanon (mountain passes that Israel can, and routinely does, control via airstrikes. The Kurds are also pushing into Deir Az Zor (circled in yellow), and if they succeed, Iran will lose its primary supply route to Hezbollah (they will be forced to run the gauntlet across the Syrian desert, within easy reach of US bases).
The best case for Assad is that his poorly paid troops can hold Homs, allowing him to keep a rump state (the blue circled area). If he can't, expect huge bloodletting as the hated Alawites reap the whirlwind of their 50 years of oppression of all the other groups.
The future of Hezbollah, Lebanon, and Assad depend on what happens in Homs.
For Israel the safest result is probably that Assad holds the blue circled area in his hugely weakened state, while the Kurds take enough strongpoints in the desert to cut the Iran-Lebanon routes, or to funnel them such they become easy pickings and unsustainable.
As for Iran, there is really no best case scenario for them. They have lost most of their ability to sustain or resupply their militias in Syria and Lebanon en masse, even if things stay as they are.
This map explains why capturing Homs is the end for Assad: The large lake that extends from Homs to the edge of the Anti-Lebanon mountains means that the coastal Alawite zone will be connected extremely tenuously to Damascus.
The map is incorrect as the legend states an Israeli-occupied Golan Heights. The Golan Heights are not occupied, but was annexed in 1981, so it is a part of Israel as recompense for a failed military war. Doesn't matter if Arab countries want to recognize it or not, it's non-negotiable and after 45 years will never be a part of Syria again.
These maps explain a very great deal very clearly. Thank you