1. Most colleges are looking to add sports (if they are willing to add sports at all, some schools are dropping them) that are already sponsored by high schools within their recruiting areas, so you probably won't see extreme sports at the college level until you see them proliferate at the high school level.
2. Extreme sports are, in my opinion after 20 years in college athletics, increasingly popular because they are participant rather than coach/youth club/parent driven. But without coaches, clubs, and political infrastructure, it's tough to campaign to have your high school add skateboarding or whatever as a sport. Not only that, having a high school extreme sports team would really change the dynamic in terms of these sports... so even participants in these sports are somewhat leery of "joining the mainstream."
Until there is a grass roots push to add these sports, few Athletic Directors, who have no background in them and are risk averse, are going to want to stick their necks out.