I've always wanted to see that Link/Malon ending.
Anyway, WW's world is strictly connected to the events that Big Link experienced, where Ganondorf was defeated 7 years after Kid Link got the Master Sword. If we look at the timeline Link jumps thru, Big Link was the one-and-only Hero of Time and physically belonged in that Ganondorf-influenced Hyrule. However, "Almost-legal" Princess Zelda in her "infinite wisdom" (Triforce, my butt) sent Link's arse back 7 years, essentially physically removing Link from their universe and eliminating any meaningful involvement he'd have in their future -- because Link is now physcially lagging behind by 7 years -- that's why the Hero "didn't show up" in the precedents to WW. Point is: IT'S ALL ZELDA'S FAULT tHE STUPID *#&%@.
Now, MM is of course connected to Kid Link after he was returned to being a kid, specifically before Ganondorf chased Kid Zelda outta the castle. It's funny in a Tom Hanks/"Big" sorta way cuz Link got to experience what it's like "to be a MAN" even though his mentality didn't mature at the same time his body did, anyway... The problem is it isn't clear whether or not Ganondorf was a threat, or if he was there at all. What signaled Link that it was OK to run off (and end up in Termina)? It sounds like Kid Link and Kid Zelda teamed up on Ganondorf and defeated him then and there, if he was around at all. Or it was like "ok Link, there's no bad guy to defeat so you can run off wherever you want, oh, take the Ocarina of Time with you." Whatever happened, with Kid Link and Kid Zelda practically able to run around for 7 years together, the events in the latter part of Ocarina of Time most likely would not have taken place, and we're now working with an alternative universe, where the OoT/WW universe moved along separately.