[mvonfr]

All of what you said, plus also : I'd expect to see Russian S-400 installed in Iran, Syria, and perhaps even Turkey before long, some of this has been done already.

S-400's in Assad's hands will keep the US Air force out of Syria, making supplying the Kurds very difficult.

As for the Kurdish Air force .. well, a few drones can always be smuggled in .. that's about it.

[PIF]

S-400 systems were installed months ago at Russia’s Tartus, Sryris air/naval base as well as S-300 systems aboard various naval assets off the Syrian coast. And they are currently installing S-300 and S-400 systems on the Iranian base they are using. GRU Spetnaz and T-90s guard them.

Turkey would be the next up - unless they install some at the air base they are sharing with the US in Iraq (probably too provocative).

Any Kurdish drones would have to come from Turkey (Israeli tech), Israel, Iran, or Russia - none of which are even remotely likely to sell.