I agree this makes sense from a fiscal standpoint, in being able to syndicate ST-HD.
From what I understand, they would literally have to reedit each episode, after converting it from film to HD video. This was the process they used originally, a fairly new concept at the time. I'm pretty sure all of the effects were shot on film, and thus would not need to be redone.
As for 16 x 9, everything was shot on 4 by 3 stock, as far as I know, so it could be cropped, I suppose — unless it was shot with anamorphic lenses (which I wonder about...since I can't recall whether you see the little Panavision bug in the closing credits or not).
It will happen, and it will likely happen sooner, rather than later. By the time DVD-HD/Blu-Ray is an issue, players will be cheaper and the format war will likely be over.