There is no oficial roadmap or plan. Gidgreen asks from time to time which new features or improvements users want and depending of the input he adds the one or the other feature.
Besides, in my opinion You are fully right. Q2A is such a good product that it would make sense to open it more for community like projects. Within others a few features like all events on a personal wall page (fblike), mutual friends/followers, new post types like articles or blogposts, merged user pages, flexible media fields, more flexible email system, group or circle features (g+like) should be part of the core.
I like the plugin system, but many things still could be added to core. For example, having an article or blog-post feature could be done through plugins, but it would be much better if new post types like articles, blogs, galleries and such could be defined through the original script.
Gidgreens script is now installed on 10.000+ sites, great so far, but having the most wanted features like community, media and blogposts, could make q2a very fast one of the widest spread scripts ever.
I think gidgreen does see that very well and will, as before listen very well what we, the users have to say once asked for our wishes for the next release.
So, I stay with q2a waiting some really good stuff to come.
To get hands on a extended "core" community / media like edition I even would pay.