The general principle that seems to have been established in the past is that plugins should remain until they break, or some major problem is found with them and nobody wants to fix it.
It doesn't break but just thanks to the fact I spent a significant amount of time adapting it to the new tag manager API (and in not a very nice way because if I did it properly, I'd have to rewrite half of the plugin) which is the kind of work I'd like to avoid in the future. And because the code is slightly messy and hard to follow, I can't promise I didn't break anything (well, it seemed buggy already before my patches).
In particular does 1) GeanyPrj write any project info and 2) does Project Organiser read that info. If 1) and not 2) then its particularly important to keep it as long as its working (as well as it always did) so old project files can be used.
1. yes, 2. no (no plans for that).
In general I have no trouble keeping it in the plugins project, it's just when we were talking about it with Frank and Matthew, they were inclined towards removing it but suggested to ask on the mailing list which is what I just did.
Cheers, Jiri