The idea of the call to adventure does not have to come when the protagonist is young but is preferable. A scenario of the old link can occur this way. Young link has the experience of the call to adventure but rejects it along the way upon forst meeting the a magical helper or old sage (first dungeon) a misfortune is cast upon him whether through injury to himself or a loved one and his call is ceased. Link goes back to the area of the known world to continue his life.
As time goes on a great cataclysm befalls his known world sending it into chaos. Many years habe passed and link us old enough to pass on his legacy but it has not happened. he is old and battle weary as although he refused the call he chose a different life as a soldier. The call to adventure is set for a second time when the son of his childhood love who he never wed is taken by a great evil while trying to save his beloved.
As a promise that he has made in the past and in repect for his past love he embarks on a quest to save and protect the young lovers but is once again called to adventure, to fulfill the duty of his destiny. Once again he meets with. the sage and you go back to the origin of your first trial (first dungeon) where memories of the rejectiom of the call come flooding back.
Memories of regret and a lust and desire to fulfill one's destiny come flooding back and a trial like no other is placed on the protagonist in which he passes while also learning of the seeming connection of the young lovers and his own destiny. Deep in the forest out of place and out of time, the old link finally accepts the call and is violently flung into the abysss.
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Imagine what would happen if peter pan grew up and was called back to neverland having only ever experienced it once as a youth, then to be called back as an older man seemingly out of place to his own calling.
Thematically it is something that the directors of the game are probably going through now at this stage of theor life and it might relate to them in a way where they can write an old link story. it will end with an oot ending seemingly but it will be bitter sweet as it will fulfill the destiny of the old link to his death as a sacrifice to save his world but the reward is his eternal youth in death to bear witness to the final battle against the great evil.