Regime change is best instituted internally by home grown...

Regime change is best instituted internally by home grown actors. Iran’s Ayatollah was not targeted for this reason IMO. The US wants the Iranian people to overthrow him just like the Romanians , Lybians and Iraqi’s - public execution follows with accompanying gruesome pictures spread through the population . Unfortunately what comes afterwards is rarely pretty - civil war and / or unstable society . Best case scenario is Ayatollah flees to Russia like Assad in Syria but this unlikely given the religious extremism ideology he has sprouted during the regime.

"The trouble in Iran is unlike Syria there is no opposition."

Romania's leader fell because of the disintegration of communism - Iraq and Libya leadership fell as a direct result of American intervention and still are both basket cases opposed to Romania.
The common denominator is, all were propped up by one or another superpower. I doubt the ayatollers have gone to Russia, this has more to do with war propaganda aimed to the destabilise the regime.
Got my fingers crossed for Syria and the new bloke can make a go of it - crazy neighbourhood and not one I'd like to live in unless I had to.

"but this unlikely given the religious extremism ideology he has sprouted during the regime"

This might be on both sides and I politely have to disagree with Iran not having an opposition - they just don't have the fire power or control the military.
Recent Protest Waves (2022–2023 and earlier)
The "Woman, Life, Freedom" protests after the death of Mahsa Amini saw millions of Iranians calling for the end of the Islamic Republic.
Protests in 2017, 2019, and 2022 all featured economic, social, and political grievances — with anti-regime chants becoming the norm.
Slogans like:
“We don’t want the Islamic Republic!”
“Death to the dictator!”
These were not marginal — they occurred in dozens of cities across the country.
Polling (When Available)
Reliable polling in Iran is very limited due to censorship and fear of government surveillance.
However, a 2020 survey by GAMAAN (a Dutch-based group doing anonymous polling inside Iran) found:
72% of Iranians do not want a religious government.
Only 22% supported maintaining the Islamic Republic in any form.
A large majority supported secular democracy.
Youth Demographics
Over 60% of Iranians are under age 35 — many do not remember the 1979 revolution and want greater personal freedoms.
Honestly I don't have the answer - maybe trump's right.
"Sometimes you see two young children fighting like crazy. They hate each other, and they're fighting in a park, and you try and pull them apart. They don't want to be pulled. Sometimes you're better off letting them fight for a while and then pulling them apart."

I could be wrong and others right, I just think it's going to go on for a long time - if you have friends and family in the region I hope they stay well and safe.