if Charles the Bold would had succeeded in gaining the Royal Crown of Burgundy, it would have been a kingdom, which was an imperial fief (like Bohemia).
Oh? I wasn't aware of that.
Border changes also happened the other way around, when the question of the Burgundian inheritance (started with the death of Charles the Bold) was solved, Flanders and Artois were transferred to the HRE.
Right. That makes the argument complete.