This in effect means that support for the current version (unless something major occurs) has ceased.
It's possible there will be an update to Pocomail 4/Barca 2.
It is my opinion (having been involved in software deployment), that there is usually a plan - so to speak. Personally I feel such a plan should be made public (at least at a high level not the full SDLC). Even a target date - yes they do change often - means that users can see that there is development going on and also that many of the issues that currently exist will be resolved. Again this is just my opinion, but from a semi- informed position with other projects I have worked on.
I agree with you, it would be very nice, I as a user would appreciate that as well. (Still as a user of numerous other applications I can say authors of most of those that I use don't make such data public, at least not the details. There are some exceptions - bright stars, the only one that comes to mind right now - of those that I use - is however an application where development is easily predictable - unlike Pocomail particularly with this large upcoming change).