What are other examples of royals who, at some time or other in their lives, had succession rights to three or more thrones? Of course, the new Norwegian heir would lose his Danish royal rights and title; but he would retain his British rights (one does not need to be a member of the royal family of the UK, in order to be a dynast there). Still, it's interesting to note that he was a dynast in three different monarchies, if not simultaneously.
Perhaps members of the Greek royal family would count: after all, they retained their rights to the throne of Denmark. So the male members were dynasts there, as well as Greece. In addition, those descended from the Electress Sophia of Hanover would have at least remote rights to the throne of Great Britain. What this means is that the sons of King Constantine II of the Hellenes would have been triple dynasts. Ditto for the man we know in history as the Duke of Edinburgh, the late prince consort of Her Majesty the British queen.
Can anybody name other examples?