Batman Beyond Crossover Idea
Partly because I like Terry McGinnis, but this could either be a time travel adventure canon in the alternative show, where Terry teams up with Nightwing and Captain America.
In this story, Terry's biological father wouldn't be Bruce because Cdmus wouldn't be concerned about Batman since there is no Batman. Ergo, Warren is his actual father here.
Since Batman wasn't a thing here, unless one takes the crossover idea with canon Batman, Terry can either be a vigilante inspired by Nightwing instead, or after meeting Bruce, he can see the Batcave (without the vigilante part) and get inspired to create Batman or something like Batman based on Bruce's story and him trying to help him with his father's death and the company corruption. I personally think the latter is pretty interesting.
As a twist, depending on Dick retiring, Damian could maybe take up being Nightwing and work with Terry.