You've probably seen this but from RAND:
Fordow is a feint.
(For brevity, I will refer to Israel+US simply as "west", because these are essentially western interests at their core, with only Israel+US doing the kinetic work.)
The west would ideally have Iran become something very different. No nukes, and no conventional threat or being western-oriented.
But pre-war Iran was something they could live with as long as nukes weren't pursued and the conventional threat was minimal. That is, it wasn't a burning issue for anyone to do a regime change.
Fast forward now, Iran has no nukes, no conventional threat, and its leadership has no negotiating cards and itself fragile. This allows the west to be increasingly ambitious with war objectives.
Factors:
- Fordow is not a difficult target.
- It is sold as such to the public, but even publicly available (including to Israel) means are viable solutions.
- Another option is a ground raid like in Syria in 2024.
- Both have developed classified weapons and methods over several decades with a focus on Iran.
- Too many assets in the region for just a Fordow strike. Preparations could have been completed within few days.
- Could also be a flex to Russia and China.
- Khamenei hasn't really much to offer.
- Operational superiority in Iran invalidates assurances provided by IRGC.
- There isn't really a worse claim to power than IRGC.
Whether or not to keep Khamenei and IRGC in power therefore becomes more of a question of whether the west considers now the optimal time for regime change, and by what method.
The west could decide on a costlier and longer method that would reduce risk to civilian casualties, particularly against the strategy of IRGC living and hiding within residential areas. This would be important in gaining public favor and permitting higher level of coordination for an uprising and takeover.