Short of an insurrection like in Syria, the khomeinists will stay in power.
Even a Syrian type situation is extremely remote because only 10% of iranians are sunnis opposite to the 75% in Syria. So no sectarian based insurrection.
This leaves "popular" insurrection, but with no organized base, no political parties, diffuse infiltration by state security, there's no hope beyond sporadic demonstrations.
The khomeinists will crush any protest from the beginning knowing they have nowhere else to go in case their regime falls.
There can be regional nuisance situations in some areas but the regime won't have any problem in exterminating any real threat.
Khomeinists are there to stay .. they just have to survive until some bleeding heart like Sanders (heaven forbids) takes power after Donald's fall.