There are lots of things I would like to find, yes including the disks and actually dangerous black holes and lots of other stuff......maybe one day when they manage to sort out the issues with modeling and lighting with what they already have. I would like them to fix stuff and push forward with future plans at a steady pace, add extra stuff like comets, maybe Oort Clouds, be fun dropping in to one of those regions. I don't want them to stop working in fixing and improving current stuff and pushing forward plans for more planets to be landable.
I also want planet specific species rather than generic across the galaxy so that will require some procedural work there, abandoned alien cities and space stations, maybe when we get EVA so we can explore them, water on planets, lava as well, lots of stuff. It may be it never eventuates in ED as it is but we have to wait for an entirely new game, if that happens it happens.
I think proto-planetary disks are probably not on the current roadmap.