Term "Tribal" being used on Steem appears to be Communities headed toward Niche platforms where Tokens are on offer.
@palnet - testing this due to only quality content creators being invited, PAL has always assisted many over the years offering a helping hand, I like the team, you earn PAL tokens.
@travelfeed - new start-up offering travel bloggers a home earning Flights, working with @steemitworldmap using new categories to distinguish exactly what one might be looking for, such as camping, hiking, holiday destinations; inland, mountains, beach, wildlife etc..
@beerlover - a love of sharing beer content once a week, what is fun is you are able to reward !BEER Tokens to deserving authors, whether beer related or not.
Many new tokens appearing on Steem-Engine, even the above I have not fully tested the in's and out's, but am happy to mention since they appear to be creative, in topics I enjoy.
This does not mean you abandon Communities you currently support, it may mean you will need to check tags carefully or use different front-end platforms to get to the right Tribe.
This is my take on what or how tribes are evolving, if you are a gamer you will join a gaming platform without having to wade through posts on tasting food, some will gain in popularity others will fall by the wayside.
We are all still working together on the blockchain with new ideas evolving.