They're not immortals. Probably they would take care of Taesun until his dying days. And I think that's okay because the biggest love you could receive from someone is how that person color your life and how you bring it forward. Taesun also would die happy knowing he has live his life in warmth with his family.
Yeah that's what I understand. I want to make everyone sadder by saying Geumryang will probably follow suit Taesun after that. Cause Taesun also is the reason why he sort of revived back from the brink of death. The original idea for the story is for Taesun to bear his offsprings so that they could take over his role at the mountains.

im not tryna make sad anyone but... in the future he would leave behind the photos as memories cause Geumryang its a god and his sons too they're not going to grow old together