I think if it went "mainstream" by the way fans want it to be mainstream, then the pre conceptions we worry about now with soccer moms (heheeehe) getting their knickers in a bundle over these cartoons would be a non issue, because the point of them being mainstream would mean they would be taken at face value, as are all live action movies today. People as a whole would know a great deal more about animation so they would know what to steer their kids away from. And has this type of thing been a problem in the past? Do we have records of parents putting in Akira or Twin Angels for their kids and then turning around and getting all upset over the sex and violence?
So, in response to your question, yeah, I want it to be mainstream. I want there to be a better market for serious anime titles to get great theatrical exposure here, and at the same time people will take them as seriously as they would any live action movie, and they wouldn't have any preconceptions of it. If it became popular over night, yeah, you'd have problems with movie studios trying to make it appeal to the lowest common denominator, but if people are turned onto animation one by one, as I suggested in my recent Matrix thread, then I think over time it could be mainstream and it wouldn't be seen as a sudden fad.