Yeah, I love the ATmega1284P. I've made some small efforts to make that chip more accessible to the Arduino community.
My advice is to make your work publicly available and see what happens. It may benefit some people, some people may contribute to the project and benefit you in return. I think a GitHub repository is the best way to do this and will make it easy for people to contribute to the project.
I'm skeptical about the prospects of the Arduino developers merging something with so much overhead but I certainly don't have an official voice in the matter. I just did a search of the Arduino IDE repository to see what had been said on the subject and there are some things you might find of interest in the results: