Still a small list compared to the natural flow of comic and toy based concepts into animation: from the 80s GI Joe, to He-Man, Monchichis, My Little Pony (and too many to list here), to the dozens of shows based on DC & Marvel comics from the 1960s-forward, live action film's place as animated adaptations are not all that frequent.
But that's not what we're talking about. We're talking about the prospects of adapting a live-action property, Star Trek, into a contemporaneous animated series. There are numerous prior instances where that has been done. The fact that they're outnumbered by straight comics-to-animation adaptations is irrelevant to this particular point. They're also outnumbered by entirely original animated shows that aren't based on anything. And they're outnumbered by cars on the highway and stars in the sky. But those aren't relevant to the specific question we're asking here, which is whether it's feasible at all for a live-action franchise to have a contemporaneous animated adaptation. Since it has, in fact, happened multiple times, it is therefore possible. Period.
I was around as a fan at that time, too, and TOS--even in the infancy of its syndicated success--was already well known.
Yes, and it's even more well-known today. It's not as if people have forgotten it existed. The 2009 film was the 7th-highest grossing movie of the year in the US! It just doesn't make sense to say that ST was more popular or more of a cultural icon in 1973 than it is in 2013. Yes, ST's popularity has waned considerably from where it was twenty years ago, but it's still bigger than it was forty years ago.
On the NBC note, networks were and are all about the bottom line:the dollar, and for their interest in bringing back a failed series is speaks to its growth in cultural power since 1969--a recognition of a broad appeal. If NBC truly believed they were only going to deal with a handfull of ST fans, then a new series would not be in their best interests.
Again, I do not dispute that it was popular back then. What I dispute is your insistence that it's somehow become obscure and forgotten today. The fact is, CBS has made gazillions of dollars from Trek over the decades and they're very well aware that it's got enormous profit potential. So they would absolutely be interested in a new Trek series, animated or otherwise. They may, in fact, already be talking with Kurtzman & Orci about making a new animated series.