Yeah cause making a new death mountain that makes no visual relation to ANY of the Zelda Games that are being represented is viable. It isnt death mountain on a dietA) It doesn't matter how the games END. What matters is what is true throughout most of the game, or what is true in the most well-known portions (aka the beginning).
B) It isn't likely to be Mt. Aleph, because so far we have seen no evidence of SSE locations being more than generic video game levels ("forest," "desert," "sky," "mines" etc). No Peach's Castle or Lost Woods or Dreamland or anything like that. A hint that Pit lives in the sky is kinda close I guess.
C) Death Mountain doesn't LOOK one certain way so don't use that as an argument for or against it - theres a mountain called Death Mountain in lots of Zelda games, and they all look dramatically different.
So we really know, all thats left to do it to wait and find out, and then praise the OP if he/she is correct, and shower him/her in candy and puppies. Sound like a plan?