Some armchair generalling about to happen. And, yes, I know this is very simplistic. If this was in the realm of possibilities, this is how I'd supply Assad for cheap offensive attack forces for the current situation to route terrorists.
Buy:
200 Russian surplus BM-21 Grads x $1 million each = $200 million
150 Russian surplus T-72 tanks x $1 million each = $150 million
4,000 Toyota Hilux/Tacomas x $20,000 each (direct from manufacturer) = $80 million
Build 4,000 replicas of the Chenowth Advanced Light Strike Vehicles x $10,000 each if built in-house and without profits = $40 million
Buy 4,000 Zero FX electric motorbikes x $8,000 each = $32 million
Add the Russian Kord .50 caliber machine gun and the Russian AGS-30 grenade launcher to the 4,000 Tacomas and 4,000 Chenowth dune buggies... about $15,000 extra per vehicle... $120 million more. So the Tacomas become "technicals/battlewagons"... same with the dune buggies which would have the equivalent firepower as Navy Seals in their dune buggies.
More Tos-1's would be nice, too, but those cost too much so we'll leave them out. Some Kornet anti-tank/armor missiles would be nice too, but we'll leave those out. Can buy sheets of AK-47 bullet resistant glass to protect the grille/engine and windshield of technicals and dune buggies from China/Alibaba for about $150 per sheet. Clamp those on.
So for around $620 million (not counting ammunition), could be more, could be less, depending on how much Russia/Iran subsidizes arming Assad, Syria would have a highly mobile combined offensive infantry and artillery force.
Divide the equipment up into 20 "Tiger Forces" offensive attack groups. This would be overwhelming firepower against terrorists who have little armor and pretty much rely on technicals, RPG's, mortars, and AK-47's.
10 Grads, 7 tanks, 200 technicals, 200 dune buggies, 200 electric motorbikes in each of 20 group... less than 2,000 guys per group. The Grads pound an area and then the tanks/technicals/dune buggies follow up by pounding it with tank shells, heavy machine guns, and grenades. Overrun the area and wash/rinse/repeat. This doesn't even account for Russian/Syrian planes or helicopters bombing the hell out of areas.
In the mountains and deserts the dune buggies and motorbikes (just dudes with AK-47's with a grenade launcher attachment) would work great. Use them as swarms to protect and hold the desert border areas with Jordan and Iraq (pro-US groups are infiltrating through the Jordanian border taking areas from Islamic State).
That's my redneck, cheap, ground fighting force solution for the Syrian Army to dominate and route the terrorists... especially if Russia is indeed taking most of its air/firepower home.
Because of Israel, Russia probably wouldn't supply that amount of Grads or T-72's to Syria. (And the T-72's are just a cheap take-what-you-can-get tank that is inferior to the more expensive T-90's).
Here's a map of divided Syria (not sure how Putin deems this as getting the job done).
http://syria.liveuamap.com
Note also, why couldn't Putin say something like "After the Syrians capture Palmyra and Deir ez Zuir from Islamic State, Russia will start pulling its forces out." Instead he essentially said Russia is pulling out tomorrow. That's bogus. He could've baited the west by saying ok, we'll be going soon but first Syria needs to capture just a little bit more from Islamic State. String the west along more but give them a light at the end of the tunnel so they don't escalate since they want Russia out of Syria.