Well first, the fork idea, is simply that, an idea, not a definite intention.
But the fork would actually be in the opposite direction, not to add features but to strip bbPress down to it's core, improve performance even further, make it more modular and make several things that are built-in now into plugins, ie. gravatars (which I have already done).
Then there would be powerful little features like immediate $bbdb query access without loading the entire core, so ajax plugins could get lightning fast responses from the server for anything in the database.
Also a way to make admin menus not load during regular runtime. They would be like the special underscore plugins, only loaded during admin. This way you can make all the fancy admin menus you want, but they do not load or execute unless a real administrator is in the admin section.
The idea is to do all the above while maintaining 90%+ compatibility with bbPress 0.9 and existing plugins. Not an easy feat, but something I've contemplated for awhile now.