Love the meta-foreshadowing of the recent B&R arc in that Damien is put in peril by Pyg - who, as we see in the opening of #666, becomes a Professor in the future, with Damien ACCUSED of his murder rather than actually doing it! Plus, you'll notice how primitive the Doll-O-Trons of this era are compared to the models of the future.
Another thing - people are interested in trying to integrate "Batman Beyond" into the DCU Earth-0, and #666 negates that...or does it? How about, instead of Bruce as Terry's secret Dad, we have artificially-inseminated Kathy Kane as his secret Mum? It'd explain the costume similarity, for a start...