Quote Originally Posted by Errorname View Post
Order 66 isn't happening without Palpatine being confident that he has Anakin on-side, and Mace doesn't attempt the arrest without intel he gets from Anakin. It's possible this averts the worst outcome, Obi-Wan being present when things turn ugly might be enough to swing Anakin the other way, but hardly guaranteed
Hard to say. The Council made it pretty clear that as soon as they received word of Grievous’ defeat, they were marching to Palpatine’s office and demanding he step down.

Kl-ADI-MUNDI: If he does not give up his emergency powers after the destruction of Grievous, then he should be removed from office.

MACE WiNDU: That could be a dangerous move ... the Jedi Council would have to take control of the Senate in order to secure a peaceful transition . . .

Kl-ADI-MUNDI: . . . and replace the Congress with Senators who are not filled with greed and corruption.

Anakin telling Windu that Palpatine is a Sith Lord may have sped things up, but Palpatine’s window was undoubtedly closing regardless. If he didn’t use Order 66 while the Jedi were still spread thinly across the galaxy it never would have worked. It’s not like he would actually give up those emergency powers anyway, right?