First of all, Super Smash Bros. Chaos FTW.
I'll try to respond by points.
I don't like the RPG-idea at all. It's just silly, "out of character" and it would need a lot of effort which should be put in other things. Subspace Emissary was fine. Give me a new story with enemies more inspired and more related to Nintendo mithology, and some jaw-dropping CGI cutscenes, and I'm fine. I don't really understand how can people complain about SE after Melee's adventure mode.
I like the idea about six-men battles, but that's risky. Mario Kart Wii expanded the number of players and did that only half way good. I would prefer this to be a special mode. For the 3DS/WiiU connection, they're too different consoles. It's not like PS3/Vita, I think it won't work well.
AR mode, if actually possible, would be fun as hell. I'm quite confident the trophy/sticker part of that will be in anyway.
Smash Master: the same, would be cool, I'm not sure it would work well though. If they manage to do that right, I'm all for it.
Online: it will obviously be like that, even if I'm not that interested in online gaming. Would be nice to see something like "US champion belt" or "Ganondorf champion belt", if you know what I mean.
Cut characters. As much as I want EVERY SINGLE character to return, it's possible that someone will be scrapped off. Lucario and Toon Link are some of them. Snake could be, even if the fact that he's not in Playstation All-Stars give me hope. Sonic and R.O.B. are safe. Sonic was so highly demanded, it would be just cruel to take him off again, and he belongs to this game. R.O.B. is just too charismatic and funny, he's a joke character and I don't really understand why should he be cut. I don't see Pokémon Trainer changing too, he's good as he is. Just add another trainer if you want another trio.
Newcomers and returning. Mewtwo really seems plausible since he's higly requested, but then why not Roy? Little Mac is OK, Lyn is not, Saki is unlikeable if you ask me. K.K. Slider would be nice but nah, Waluigi GOD PLEASE NO. Isaac has a possibility, Bowser Jr. has even more (but not along that Waluigi idiot). Ghirahim and K. Rool would be amazing, I hope they're in. Miis are a no-brainer, the Mech Gauss is original at least, I like him.
For the third party, yeah Pac-Man and Megaman are easily in. Bayonetta... Meh, I thought she had a possibility after the sequel reveal, I like her but... Nah, I think Sakurai doesn't approve. Too sexual, too out of Nintendo's style, too... much. But would be cool.
As the stages, I would come in my pants if every single arena from previous games will return, plus a new bunch. Congratulations especially on this last part of the article, a lot of the ideas are original and ****ing amazing. I like them all, seriously. Nothing to say about those. Man Skyloft will be awesome (it's in, don't be silly... it's in). Only one thing: Fire Field over Aeropolis. That's all, but these new stages would be incredible seriously.