if by mainstream you mean magazine coverage, media coverage, and millions of people doing it, i dont think that will ever happen.
if it were to happen, i think it would be pretty bitter sweet.
there would be more people to fb with, but small companies that make fingerboarding fun and affordable (alot like Pure XD) will die out. There will be bigger options that not many people would turn to buy from such companies with "less" credibility.
I wouldnt like it to be mainstream, but if it was like halfway mainstream, it would be perfect.