Hey I had an idea. Did anyone here ever watch Static Shock? It's one of the more obscure titles from the DCAU.

Anyway it had a crossover with Batman Beyond in its fourth season called [url=http://dcau.wikia.com/wiki/Future_Shock]Future Shock[/url]. Static assists Batman and Robin in apprehending a villain called Timecode. While in the process of dismantling Timecode's time travel device Static accidentally activates it and ends up transported to the Batcave of the Beyond era.

Timecode was only on screen for about a minute, he was basically a plot excuse to get Static to the future but regardless his reported plan was to make extreme bank by charging villains with outstanding warrants for a way to escape capture, this method being transporting them to the future. So I was thinking that at some point an arc in which we're dealing with a sudden influx of 2000s villains armed with 2040s technology. Could also be a way for the Beyond Titans to deal with some of the lesser classic Batman villains.