Of course not. They just do a better job of reaching out to groups who are outside the "mainstream" of America (minorities, non-Christians, LGBT, immigrants, etc.)
Keep in mind all of the above groups will essentially be the "mainstream" in 15-20 years.
Minorities are the only above group that have any hope of being "the mainstream" in 20 years, dude.
Depends on what you mean by "mainstream". For example, LGBT acceptance is increasing rapidly, and I doubt in 20 years that being gay or bisexual will be very controversial at all.
If anything, it's the opposite. Depressingly, anti-Black racism will almost certainly endure longer than prejudice against any of these other groups,