I know Japan likes him, but I've heard that they aren't quite so optimistic with him being playable in Smash, however I could be completely wrong about this.
Wherever they might land on his chances, he's still the most requested from the series.
As for him being the only Zelda character with a sub-series, wouldn't that just count for him being a spin-off character like Yoshi and Wario?
He could be either I suppose, I'm just saying having a sub-series is a big deal... Yoshi and Wario are big deals in the Marioverse.
As for the Assist Trophy Massacre, I think that Majora not using the moon as part of his attack and the return of Melee stages could mean that Termina Bay will return.
That is just speculation though. And it's not like a stage couldn't be tweaked for the sake of a character... I'm sure Alfonzo wouldn't mind Tingle leaving floating around to him while he joins the fight.
As for the remake, I'll let that pass, since I use it for Vaati all the time.
Vaati hasn't been in any remakes, Vaati was in a glorified re-release.
Also, doesn't Zelda not sell quite so well in Japan, but better in the rest of the world? Wouldn't it make more since to add a character the West doesn't dislike?
You'd think that, but then why did they choose to remake the Zelda title that appealed to Japan the most? Zelda isn't at Metroid or Punch-Out levels of bias, Japan still likes the Zeldas Tingle hails from. If there was another Zelda character who had all Tingle has in his favour, but was adored by all regions, sure, by all means include him over Tingle... but there isn't.