The Zelda franchise is likely one which will never end. It's a legend as the namesake suggests. Link will embark on never ending sidequests to rescue the damsel in distress. The franchise would solely be terminated if Nintendo went down under as Miyamoto, Aonuma, Iwata and others have hinted that the series will not appear outside of Nintendo platforms.
But what if there was a final Zelda game? The consummate end to all things. This is an interesting question. I'd personally love for the game to be closer to Ocarina of Time in terms of presentation, gameplay, sound, and replay value. An expansive and nonlinear overlord, a fully functional musical instrument, numerous dungeons and hidden collectibles. Taking note from Skyward Sword this title should also pay homage to the entire series through cameos from fan favorite characters and numerous story references to past titles.