I believe more and more people will escape to lemmy sooner or later, and I already see 3 different communities for the same thing (selfhosted) here on lemmy. Time will tell which one will be the most active, but lets assume all of them will be equally active and the desire emerges to combine the two communities about the same thing, is that something possible or intended to be possible with federated services?
The down side of that would probably be duplicated content. Like if some major news happens for a topic reposts can already be really annoying and usually need moderator action to combine threads. Then there’d be that times however many communities exist for that same topic.
As another pointed out, that already happens. It’s even preferable, to some. For example, I had a programming multi reddit with JavaScript and several more focused JS related subs in it. Seeing the same link or topic in multiple subs often let me get more viewpoints to consider. Outside of the web, journalism outfits all publish Associated Press articles. If you follow multiple news outlets you’ll see the same story that way as well.
To me, it’s just natural.
We deal with that in Reddit too though. I see your point but if people are subscribing based on user count then eventually the best community will win I guess?