Sorry for originally posting this in the wrong section. I thought since I was asking people where they thought the Deity Mask came from and what were it's origins that this thread would be theory, but I was wrong. I'm not too good at judging those kind of things. Sorry for that. But thank you DuckNoises for moving this to the correct place. I will try to keep my threads in the right spot.
Anyway with that out of the way; I don't think adding a game involving Deity Link would mess up the timeline. It would change it a lot, but it would still work its way in. I mean look at some of the other games that had little to no relevance in the timeline, they still made it in and did not destroy the line. As long as Zelda fans support a timeline it will exist. But I do see how it would cause complications in the timeline, but as I've mentioned these would eventually be overcame. It would just be cool if a game allowed the player to obtain the mask again and use it. Honestly I thought as a child that the mask showed us future Link. Stupid thought I know, but I was only like 9 or 10. I thought that since Princess Zelda sent Link back in time in OoT, and he traveled to Termina he had altered his future. Thus the Deity Link was who he was to become later in life with the current time flow. Though as I got older I found MANY holes in that idea. Mainly; How would there already be a mask of what Link would look like in the future if no one had gone to the future and saw Deity Link? Not only that but how and why would it transform Link into Deity Link? Today I think the mask was created simply to instill power to the wearer. Not just to Link. Anyone who wears it will transform into a Deity-like person. They will not all look as Deity Link did though. They'd have the white clothes, and the face paint, and such, but their looks will not completely change. But of course Nintendo did only put the mask in to be a reward, but it's still fun to try to place it in the Zelda world somewhere, and if it is successfully placed there it means it had to have a creator, and an origin.