Afrin Canton is only about ten miles across, and now Turkey has been able to move artillery and armor up to its border on the Southwest, through Idlib Province in Syria. So all of Afrin is under Turkish artillery range, and the Turks could attack from three sides.
There is no land line of communication to resupply Afrin (except through Syrian controlled territory). The only resupply that the West could provide would be by air, or through Kurdish smugglers.
If the Kurds lose, they (and their families) will have to deal with the depredations of the jihadi mercenary militias that Turkey is using (former ISIS and similar types) in that area.
The Syrians/Russians/Iranians might be willing to trade off Afrin to the Turks, in exchange for Idlib, or just to reduce Kurdish or American influence. Also, Turkey might just be using the threat of invasion, as leverage to get the Americans to pull back on their train and equip policy for the SDF (the establishment of a permanent Border Force).
I don’t believe the US will abandon the Kurds.
I don’t believe anyone considers Erdogan an ally. Not even Iran.
I’ve already seen 2 Turkish tanks in flames for attempting incursion into Afrin (Efrin). Saw video of TOW used to kill it.
With what has reported to have been given to them, aircraft are exposed too. There were 2 helicopters shot down in Turkey by the PKK.
I remember how great Turkey did in Al Bab (sarcasm). It was said they lost 50 tanks trying to take the town before they made a deal with the Jihadi’s.
We wait.