In the past, they've adapted a mix of recent things like the Superman/Batman
comics and more classic things like Superman: Doomsday
and Batman: Year One
. Hopefully there will still be some older projects getting adaptations from here on in.
You know, what I'd really like to see from the DC Universe DVD line is a movie or two (or more) wrapping up Young Justice
-- distilling the high points of what would've been season 3 and giving the series some closure. And maybe a Batman: The Brave and the Bold
movie. B:TAS and The Batman
both got movies, so why not TB&TB?
But they seem to be committed to new continuities rather than revisiting old ones -- since they rewrote Crisis on Two Earths
to be a new continuity rather than the DCAU movie it was written to be.