I disagree with the dichotomy presented. People who like a specific, niche culture aren't necessarily closed to other cultures, and people who like mainstream culture don't necessarily like most cultures and don't necessarily get along with everybody. As such, this is the progression I've watched happen:

- Niche possums and niche otters create a small community focused on a specific culture

- Otters from mainstream culture enter the community, and are welcomed by the niche otters, but this opening is disliked by the niche possums.

- The niche possums either try to moderate the community more heavily, or leave the community.

- The community grows in size, being overwhelmingly filled with otters. Mainstream otters dominate as they are more numerous.

- The community's content and culture gets shifted from niche to mainstream culture.

- Mainstream possums join the community as they identify with the community's new, mainstream culture. This completes the community's shift from niche to mainstream culture.

- Most of what remains of the community's original, niche culture is suppressed by mainstream possums, as it goes against the community's current culture.

- Niche possums create a new community, and the cycle repeats.