That all could well be true. That said, I believe vimm is relatively new.
Plus, as you said, the replacement might be something completely new. Where there is a void, there is opportunity.
Or perhaps, the development teams of those projects see what is taking place and step up their game.
It is like the blogging interface, Steemit was (and still is in the lead) but there are other apps that far surpass it and are starting to get users.
We could see the same thing in video.
Out of curiosity, what are these other apps? (all the ones I've seen so far sucked)