I would invest in several Open Source, like maybe KlyDE, but mostly Qt stuff. I would like a DE that written in Qt similar t XFCE but instead of X.Org I would want Wayland or Mir(I would also invest in both these) once the software is to my liking (a very difficult thing to accomplish) I would create an OS based off Arch written mostly in QT with great Wine integration and the works. I was also thinking of making an All-in-one emulator that acted as a hub for all your other emulators, essentially it wouldn’t be an emulator at all but more like a singular GUI for all your emulators and a Rom manage to boot. When you want to add an emulator it would show you the compatible ones(most likely only Open-Source emulators) then it downloads the emulator, sets it up, and when you want to play a game you just download it and play, kinda like steam but for roms.