We already know what happens
With another series being set in the Prequel era, it means there’s no real mystique about how it’ll all end. Sure their individual fates can be something unknown, but we already know where the state of the galaxy is going and the futures of the Alliance and the Empire.
Stories that are prequels lose a little luster as the ultimate outcomes are all already decided. We know the Empire will rise to a dominating power in the galaxy and the upstart Rebel Alliance will rise up to fight against it. Throughout this new series, we may ultimately learn this elite clone troop’s place in it all. If they are truly mercenaries who take the highest paying job, they may indeed work on and for both sides.
Whatever role they take on in the new world, will be decided fairly early in the series. After that, any outcome about the major powers in the galaxy at the time of this show has already been revealed. There is no larger picture to care about, and that makes the overall scope of the show very small and uninteresting.