Spare us the pseudo-intellectual bullshit please. Those 'Urban Dictionary' (humorous) definitions of 'mainstream' were in fact quite accurate, and I'd hazard a guess that they reflect the opinion of 90% of the people using this site.
Let's get back to the actual question: Is Garage trendy? Tough call. Depends what your definition of 'Garage' is. For me personally, No it's not. A lot of bands currently playing under the 'Garage' umbrella aren't really floating my boat (because they're not really 'Garage'), and they're also not making waves in a big way culturally.
As a side note: did any of you notice the inclusion of The Sonics version of 'Keep A'Knockin' in the debut episode of 'Pan Am'? While I thought that was kinda cool, it also irked me somewhat as it was anachronistic: the story takes place 2 or 3 years before the song was released.