There ya go, quoted the whole thing for you, not that it actually invalidates my point in the slightest. I'll go point by point.
-Impa's eligibility wasn't a realistic thing until SS was released, which was after Brawl. This is clearly important when discussing out-prioritizing, since you can't just say "Sheik hasn't changed" and pretend that means nothing else has. Who said that Impa HAS to be the one to replace Sheik? This is what you don't seem to grasp; The same issue that is going on is the SAME AS BEFORE:
Was Sheik in a game since Ocarina of Time?
Brawl: No.
Now: No.
Can she be kicked off for the sake of relevance?
Brawl: Yes.
Now: Yes.
Is there someone else that can theoretically take her place?
Brawl: Yes. True Midna.
Now: Yes. Young Impa.
Nothing has really changed. Sheik is still as "irrelevant" as she was in the past, and once again, there's a relevant option available to replace her. Yet, Brawl didn't replace her. Why does it seem reasonable for it to happen now?
-The very fact that nothing new has happened with a character that might get replaced is in itself an argument to replace it, not the other way around. And yet Brawl didn't. Seems to me the whole "might get replaced" thing is a load of bull****.
Brawl also didn't replace Ness with Lucas, despite that being Melee's original plan. No, Lucas was added alongside Ness, despite Ness not being in Mother 3 and not having a game since 1994 (so longer than Sheik).
-By your logic, nothing that could have changed for Brawl but didn't will be different in the next Smash game. Chances are that's wrong. Ok then, Captain Falcon could have had his Falcon Punch replaced with his gun, but it didn't happen. By your logic, he will have his gun instead of a Falcon Punch this time.
I have to go, but since I've literally never seen you concede a point or admit that you're wrong, I'm not really holding my breath. Then you haven't seen enough. I have conceded points and admitted my errors when people actually give me a reason to. You haven't done jack squat to warrant it.