With regards to incorporation into the core of Flightgear, the license is all fine but I ran low on energy as I did not sense that the Flightgear community was particularly excited about the idea.
Honestly, as far as excitement in the community goes, osgearth scored pretty high. There's a fair number of users who have expressed interest early on, there's frequent questions when it will be available, there's to my knowledge an in principle agreement core developer side to accept the patch, although I understand there's some technical concerns which need to be ironed out (and I remember you stating 'The ball is in my court' at some point).
Just to give a sense of perspective - Advanced Weather was greeted by a combination of 'This will never work anyway, we don't need another weather system, Nasal is too slow, you're wasting your time.' What the heck - I did it anyway. ALS to this day continues to be greeted by some as 'Crap, against the spirit of Flightgear, taking away resources from really important developments, ... The realistic radio propagation model patch met outspoken opposition from some core developers even in principle which was why it was dropped. I'm not sure what you did expect to happen.
The FG community is very diverse and yes, not everyone is excited. Personally I am unfortunately not, although I recognize osgearth as a valuable feature for some use cases and know that others are. But I am personally interested in modeling detailed interaction between weather, light and terrain, for which any form of photoscenery is simply not suitable because it's always taken under some very specific weather and lighting conditions and I need procedural textures instead. Moreover, I don't have the bandwidth at home to get imagery sufficiently fast, so I can't even try. Which for me is the show-stopper to help you with shader work - I would in principle be ready to help adding some ALS support to osgearth, but if I'm not able to use it in the first place it's dead on arrival, I simply can't develop shaders without being able to run them.
So, what won't happen is that the whole development team drops all they're doing and helps you with implementation of a feature. Hasn't ever happened and won't ever happen to anyone (if only because there's so little time in the first place and people need to priorize). The way this works is that you need to push for what you consider useful, and you need to take care of the details as well, and even in the best case there's resistance and inertia. But if you have a good case, you will be able to find people who can help you with some aspects of the work.
I mean, it'd be nice to live in a world where you can do some feature halfway and then someone else meets you on the other half picks it up and irons out all the pesky integration details. Unfortunately that's pretty difficult (which is why I rarely do it myself) - going through someone else's code, trying to restructure and adapt it and fit it in properly is pretty time-consuming. But ask yourself how much time you'd spend with code from someone else you're maybe not personally excited about, trying to merge it into a larger project and you understand they why.
I guess ultimately it's up to you - the level of excitement in the community is there to make it happen in principle, but the enthusiasm has to come from you - you need to want this to happen.