Malte,
Thanks for these great suggestions. Now we just need some TIPs, and some volunteers to work on these proposals.
One requirement of the roadmap is to have concrete proposals with a commitment and plan to accomplish them. There is also a place for general direction goals that are less specific and farther off.
I also think we do want a section in the roadmap for non-core features and applications with the same requirements. That is, proposed features with commitment to finish them in the near future, and more general goals with a less specific timeframe.