Well I always thought that TNG did shake the 'only for nerds' stigma.
I know a lot of adults who watched TNG during the 90s and they aren't Trekkies by any means.
TNG was just a damn good tv show in the 90s and being that it was able to reach that mainstream audience.
I mean TNG's series finale is considered one of the best finales in television history.
Yeah, some Trekkies are considered 'nerds' but IMO there are plenty of people out there who could be Trekkies and not have that 'nerd' title. Plus there are plenty of people who just enjoy Trek and they aren't Trekkies/Trekkers/Nerds at all.
I just don't think Trek has reached the audience size as Star Wars. That's something I hope is accomplished with this new movie.