Isis is minor imo, they were a rogue group that went off script and the US punished them with the coalition, much like what they did to Saddam when he went rogue and they created a coalition to make an example.
The bigger issue is there might be a hidden agenda to move Kurdish militants from Syria to Iraqi Kurdistan and then to Iran.
A lot of the Kurdish militants in Syria are foreign (from Turkey, Iraq, and Iran), what US, Turkey and Jolani are pushing for is to force them out and then merge the local Syrian kurds with the internal security forces. Weirdly enough Barzani was recently involved in the SDF-Jolani negotiations.
These are just my thoughts if Iran is the next Hotzone. In an ideal scenario for Iran there is no deal between Joulani and SDF where portion of the PKK or SDF are moved to Iraq.