Die Zukunft bereitet mir Kopfzerbrechen, wenn ich daran denke, dass Prinz Felix dann das Land regiert.
I wonder if the dann here has a meaning close to einmal {someday/one day}. I was under the impression that dann usually means "ein bisschen später", but can it also refer to a somewhat distant future such as "some years later (when the prince has grown up to be a ruler)"?
The meaning of "dann" is "at the indicated time", in this case "in the future". The construction of the phrase implies that the specific future that is causing the author a headache is the time when prince Felix will rule the country. There's no indication as to how distant that future may be, except of course that prince Felix would have an age at which one could already judge his ruling qualities.
