Why the Iranian regime is incapable of reforming from within

The unprecedented strength of the Iranian opposition People’s Mojahedin Organization of Iran (PMOI/MEK) in Paris and Albania has severely alarmed the Iranian regime. It has also raised a pertinent question, can the Iranian regime be reformed within?
https://english.alarabiya.net/en/perspective/features/2017/07/13/Why-the-Iranian-regime-is-incapable-of-reforming-from-within-.html