IRG will not allow it. Good I guess, Iran under current regime is destructive for sure but if a secular regime is to replace the Aytoallah that is not good for the region. I mean 100 million people (huge manpower), geo-strategically located and lots of resources. The country will compete with the rest of the region which is something GCC countries don't want.
My personal impression is that Iran society is much more diverse than simply mulla and liberal composition.
There are Baloch, Arabs, Azeris, Turks, conservatives, liberals, atheists, and most of above the poor of the country, at the moment it appears that they are all united against mulla clergy, but may not remain united in case, mulla clergy collapse.
Infact, i see instability soon after collapse of mulla clergy, with potential of balkanization of Iran, but this situation, should be exploited by Middleast, Pakistan, Turkey and Azerbaijan united, for their own peace and humanitarian reasons.
At least Saudi Arabia and UAE should convey strong message to Pakistan, for disabling all sort of manpower support to mulla clergy, in present and any future situation.
I agree that mulla clergy doesn't seems to be going any where, as long IRGC exist.