For anyone who didn't see lasconic's post in the forum (https://musescore.org/en/node/70006), I have been working on a roadmap document for future development. It is based on the document that was developed for a recent-ish Google Hangout, but is also augmented by things I threw in there because I thought they seemed like good ideas.
It is by its very nature not complete, but it is now as far as I plan to take it at this time, and as far as I am concerned, anyone who wants to edit it further is welcome to do so. Here is the link:
I still have no ideas on how we can best manage prioritization or deciding who works on what; I guess discussions on this list or IRC or the forums will continue to suffice as they have in the past.
I personally plan to look at the items in Accessibility and Linked Parts, hopefully in conjunction with anyone else who wishes to help. Aside from that, some of the other line items I am thinking of dealing with myself incldue one-sided ties, system dividers. Mid-score staff properties changes (especially with respect to transposition) are also very important to me, but my understanding is that Werner is already planning on looking at this. If not, I could take that on. The chord symbol editor seems like a logical choice for me, but I don't prioritize it so highly. If the old code turns out to be largely usable, though, maybe.