Star Trek was intended to be viewed on a color NTSC television. (There were a few film presentations, but it was always meant to be a TV show.) DVD pretty much saturates the quality available from such a set, so I'm happy with the TOS DVDs. The original episodes -- insofar as the DVDs reflect those -- will always be available, as long as there's one Trekkie left to make a copy of them. Now that we are "upgrading" from the producer's intended medium to something better, it may be appropriate to insert better visual effects.
What it will come down to is this: Will the new animators set out to make better-looking TOS material, or will they set out to make something new and jam it into TOS? How much restraint and faithfulness will they show?
In short, don't get angry yet. Get angry if they crop it to make it 16:9.