For the record (and this is probably due to lack of clarity on my part), the "(not Toon) Link" portion of the title is not necessarily meant to say that I dislike Toon Link or even want him replaced in any upcoming Smash Bros. I simply meant to clarify that I wasn't talking about Toon Link, and was instead referring to Young Link (in particular, the Link from Majora's Mask). I prefer other versions of Link to Toon Link, personally, but don't have a major issue with the art style. Though I am a huge fan of WW, I think I like that style of Link better in handheld titles.
I also wasn't saying I think it was going to happen because I know it isn't (at least not in the upcoming Smash Bros.).
For those saying Young Link is not relevant, I strongly disagree. OoT is arguably one of the most well known, iconic Zelda titles, and as Link from MM is the same Link from OoT, he would be easily recognizable. I would argue that this version of Link is more relevant then TP Link (since the OoT remaster is more recent than TP). Toon Link in the upcoming Brawl is fitting and will help give new fans a sense of unity in regards to the Wii U's rather meager gaming library, so I understand. Of course, a remake/remaster of MM would definitely help the odds of my dream becoming a reality.
Another thing (sorry, I'm on my phone and find it difficult to quote people) I noticed someone mentioned was how his transformation would work and compared it to the Zelda/Sheik model (or said that might be the only way it could work). I think the best set up to mimic would be the Pokemon Trainer (who, I'd like to point out, isn't overpowered IMHO). The difference would be, of course, that YL would have four playable versions as opposed to PT's three. Another option would be to have them cycle through, perhaps pressing down + B to change into a Deku, Goron, and Zora respectively. The time you could remain transformed could be limited, or you could be returned to normal after receiving a powerful blow from an opponent. I see a lot of options for it that I think could work out fairly easily, but that's just me.