I don't think TOS was peak Trek. Of course, it started it all, and it was popular in its day-to some extent-but it also got canceled after three seasons, and was saved from being forgotten or made a curiosity of the 1960s by syndication. I think 1994 was the year of peak Trek, with TNG going to the movies, DS9 on the air, VOY in the wings, and Kirk and Picard on the cover of TIME magazine.
If people didn't continue to watch it and syndication the channel that purchased the syndication package wouldn't have continued to show it for the next two decades.