1st: Never said i wanted ZSS to be cut. She could easiliy stand alone without the suit. All she would need is a final smash. I already gave my reasons for not wanting characters to switch out mid battle.
2nd: If you didn't know that was Impa in Skyward sword then that's your stupidity, not mine. I'm pretty sure everybody else noticed her.
3rd: Sheik having a big role in Oot has no bearing on Impa being less noticeable.
Sheik does not "push Impa into obscurity", she simply doesn't have as big of a role as her in that game.
4th: Impa has been in more than just Skyward sword and OoT. She's been in 6 games.
She is 1/7 characters that appear multiple times throughout the series. The other characters are Zelda, Link, Ganon(dorf), Tingle, Dark link and Vaati.
5th: Using the fact that Sheik was given a TP look to keep up with Zelda's TP look in brawl gives absolutely no evidence she was planned for TP.
6th: When I say relevant, I'm talking about within the Zelda series. OoT3DS is still the same game story-wise as the OoT from 1998. Appearing in the same game doesn't make her any more relevant within her own series.
Lastly: I said, I don't expect this to happen.
1st: Samus and ZSS are quite literally the same actual people, that would not work.
2nd: You completely ignored me saying: 'Seriously, what is the point of replacing characters in smash unless they were joke characters (Pichu) or were always meant to have been replaced when they got in (young link). Sheik is not a joke character, she clearly wasn't meant to be replaced when she got in, and my third reason, which has yet to happen, being universally hated in smash, also doesn't apply to Sheik. Sheik will not be cut by time-restraints unless Zelda is as well, and they won't be, because they will be high on the priority list, period.'
3rd: I'm pretty sure not everyone else knew Impa was in Skyward sword. I still don't know if it was the young woman, the old woman or both. :/
4th: Well, Sheik and Impa are both Sheika, (I've done my research :D) and Sheik is more relevant and important than Impa. This, in a way, a large way, pushes Impa into obscurity. Not to mention that people will actually recognize Sheik because of smash and the fact she actually keeps a body, unlike Impa.
5th: She is 1/9 characters, Toon Link and Toon Zelda included. This does not help your argument, because Vaati, Toon Zelda, Tingle and even Dark Link have a larger bearing on the series than her, especially Dark Link. Dark Link gets in, then I'll happily let Impa in after Oocoo!
6th: I read somewhere that Sheik was planned, and as aforementioned, the Sheika symbol was on Zelda's dress (I've really done my research!) implying he was supposed to get in. If he did end up cut (due to time restraints or something) and since he would have been unable to get into SS without looking desperate, he should be in the next Zelda game me thinks.
7th: I was also talking relevant story-wise, but not as literally as you. Sheik, over-all, is one of the most important characters in the LoZ timeline. OoT is where it splits into adult and young Link time-lines, and Sheik, in a way, created the Young Link time-line by giving Adult Link the powers to transform into his younger self. Without Sheik, we would not have wind waker, spirit tracks and numerous other games. This is improved, since the younger generation of casual gamers now know this due to OoT3D not to mention being more popular due to OoT3D meaning there will be a large back-lash by both young, old, hard-core and casual gamers if Sheik is cut.
8th: What does this mean? I said, I don't expect this to happen. What to happen?