Yeah, I think converting the show to HD would be a colossal waste of time and effort, would only serve to detract from the grittiness and classic feel of the show, and I don't think it'd be profitable either. Highly doubt that will ever happen.
However, I maintain that I'd be totally down for a brand, new original BTAS reunion movie. With a decent budget and for the big screen. I missed MOTP when it was in theaters so it's always been something of a fan-wish of mine to get another chance to experience that Batman world on the big screen. Wouldn't be the same without Shirley Walker though.