Something ROB related came out to iirc, but I can't remember what.
...Unless there's some sort of new ROB game for the NES which came out recently (which would make 0 sense o_O) I believe you're talking about his appearance in Mario Kart DS.
Anyways, as long as Zelda remains in the game, Sheik will stay as well. It would be ridiculous to take out an entire character for no reason (all the other characters taken out from Melee were clones, except Mewtwo, but I do believe the reason was, with him, there would be way too many pokemon reps in Brawl. Additionally, Lucario represents today's generation's most popular character, while Mewtwo represents the older, out-dated generation) when she fits in so well with Zelda's moveset. All 3 "Goddess" moves (Din, Farore, and Nayru), and transform, that represents her just fine. What the heck would they replace transform with? o_O
The only forseeable way Sheik would be removed is if, again, Zelda is also removed (which would not make much sense), or Zelda gets another alter ego in a future game, similar to her "Twilight Princess" self in Twilight Princess...But this is just as unlikely as her getting removed.