Video games were extremely nerdy and anything but mainstream barely over 20 years ago.Yes, but like he said, I'd imagine the west's views on animation as a kids' medium will prevent that from happening. Anime, and by extension animation as a whole, already has evolved into a medium that's willing to tackle any subject under the sun. If tomorrow, that "kids' only" bias disappeared, I think anime would go "mainstream" immediately. But that won't happen, and until it does it won't catch on with the western public.
Give anime one more generation. However, expect some more "western" material with borrowed inspiration to emerge to meet the extra demand, also.
The writing is on the wall. Anime following now is much more mainstream and available than 10-15 years ago, where you basically only had stuff like DBZ and Sailor Moon. What the next generation perceives as normal and acceptable just isn't going to be the same.