Popular revolutions will sweep any ideological base away, and it appears to be underway. The scale of the protests in the clips that have made it out have been impressive.

That's a myopic, overconfident take because the traditionalist have zillions more weapons and organization.

I’ve been looking for data on this. Has anyone quantified what the regime’s base of support actually is amongst the general population?

I can't see that it would be anything other than guesswork. Polls are unlikely to be possible with any accuracy there. This is anecdotal, but I've heard from the few Iranians I've known that much of the population lead western lives behind closed doors. Their civil subjugation seems to come from the threat of violent punishment (torture / rape / death / disappearance) and a Stasi-esque domestic intelligence network.

could almost guarantee it overlaps greatly with demographics

older conservative boomers vs. younger moderates. it wasn't old ladies launching riots about wearing headscarves...

e.g. https://en.wikipedia.org/wiki/Youth_in_Iran

Small sample, but talking about this with my Iranian friends, the sentiment among them and their wider network is that they do acknowledge that Iran has problems, that they need a change in leadership, but that they do NOT want a regime change at the hands of the US/Israel. For them that is a recipe for disaster and more carnage.

In their view, the topology of Iranians and their political views would be: 10% - pro-US regime change intervention; 20% - ardent regime supporters; 70% - pro-regime change but without US involvement.