I’ve been rewatching the original arc and the Clone Cadets flashbacks idea could work, both in a 3-in 1 cut of the Domino arc or in a two-parter.

The thing that makes the clone troopers in Rookies resonate with the audience is that this is their first mission. You can still point some of the elements that make Echo, Fives and Hevy unique, but these would be greatly served if we knew the hard work and lessons learned that got them to this stage, so a juxtaposition between Rookies and Clone Cadets that preserves the best moments of both, and IMO there are plenty, should work pretty well even if flashbacks aren’t going to be a staple of the show moving forwards.

If ARC Troopers in its entirety becomes the third act, the episode would need only one “Months later”-type time skip, after which there are no more flashbacks (much like Man of Steel where the frequent glimpses into the past catch up with the main story in the second act). I’d say ARC Troopers works pretty well as a stand-alone, but it might do best as the culmination of the entire story: we meet Obi-Wan and Anakin again after they are absent from the beginning, Rex and Cody are a part of the action which justifies keeping Rookies for their introduction, and it serves as a good book-end to Echo and Fives’s arc: they leave Kamino as graduates and return to become ARCs.

I’m gonna take a look to see if Grievous’s planned attack on Kamino in Rookies can be amalgamated with the actual invasion in ARC Troopers.