I am not the most contributive or knowledgable person here buttt....
You seem to be focusing on the release of the new version when the focus should be on making the new version releasable.
To translate I mean there are alot of things i see right off the bat that can be tweaked. And I think it's those tweaks that need to be ironed out before extra major features are added. I'm in a similiar boat about how everything should be done etc... but thats because I have no experience with github. I'm regularly learning more and more about it.
I've never actually coded collaboratively with others so it's an entirely new concept to me. If that's what your issue is then i'll tell you what i've been telling myself. Learn to github. If you see an issue then fix it, there's no dictionary of what code needs to be fixed or where exactly it is; that i know of. So, pick something and work on it. For example: my pick is the registration features. In my signature i've laid out a problem I had and that i'de like to work on to fix that. (or add in my case)
No other forum software fits my licensing needs and is as secure (in my opinion) as SMF. The plugin system, the templating system, all of it would take me months to write in my own time and is beyond my level of skill (theres more than just coding skill involved; take for example the design of the database, or the UI design, or a multitude of other aspects) This goes along with project management and being able to assess the needs and concerns and then roll them out with "accomidations"
I could explain on and on and on and on. Ask yourself this: what do you want to work on and why? How are you going to do that?
Make code not war.https://github.com/SimpleMachines/SMF2.1