I honestly believe a good way to end the series would be to make a game that surpasses Ocarina of Time (even though Skyward Sword should have done that already). In it, it should have Demise be resurrected and revealed to be the true mastermind behind all of the events in the series. The question is, which timeline should it be in? The Child Timeline is a good one since it's the result of Link defeating Ganon in Ocarina of Time and preventing his conquest in the past. Plus, Skyward Sword has some pretty strong connections to Ocarina of Time, if you think about it... The Adult Timeline could be a good one since Ganondorf did come back, but was destroyed along with Hyrule. However, Demise's curse makes him come back in a never ending cycle, so Ganon could come back in the Adult Timeline and lead to Demise's Resurrection. The Decline Timeline would be good as well since in that one, Ganon was able to get the full Triforce once, and in Adventure of Link, he was nearly resurrected. Since Ganon's followers were still alive, they could find another way to bring him back, and in effect, bring back Demise. What do you guys think?