Star Wars: The Clone Wars - Is THIS What Happens To The Bad Batch After Order 66?
The Bad Batch probably can't be made up of the same members as Task Force 99, since the Task Force was formed in canon in the year 2 BBY, 17 years after Order 66. However, they likely took inspiration from the team in-universe, modeling themselves after the Bad Batch. Task Force 99 creator Jason Aaron confirmed that he took inspiration from the Bad Batch when writing the Imperial Task Force, explaining an out-of-universe reason for their similar name. Perhaps Aaron's inspiration has some in-universe truth to it as well. Maybe, after Order 66, the Bad Batch served as a prototype version of Task Force 99.
Like the Bad Batch, Task Force 99 features a group of individually specialized troopers. One member is physically larger than the rest of the squad, like Wrecker, and another carries a sniper blaster which resembles Crosshair's.
The saddest part of this theory is the fact that the legacies of both 99 and the Domino Squad turn out to be Imperial killing squads. 99 wanted nothing more than to help his republic, so seeing his name stand for an Imperial troop might break his heart. Similarly, Echo, the only member of the heroic Republic Domino Squad to survive until Order 66, seems an ironic inspiration for so vicious an Imperial instrument.
Even now that it has ended, Clone Wars still finds ways to surprise us and to fill in the gaps between the prequel and the original trilogy eras.