Then they would be twice as powerful, I suppose, and one could protect the other. Or the bad guys would have twice as much of a chance to capture Zelda.
[Spoilers, I guess?] What if Link didn't win the race at the beginning of Skyward Sword?
Then you would raise that kid to play Zelda games only. (Also please ask questions relating to Zelda)
What if Link ventured into Skyrim? (I have a feeling the arrow in the knee response is coming)
Then it would be like Pulse, that Japanese horror film with the not-as-loved remake, ghosts coming through the Nintendo network and using Streetpass to haunt us.