Personally speaking, we're already familiar with Blue team, and I'm more interested in exploring other Spartans than just trying to replace Master Chief. On another level this still gives canon blue team a chance to form, allows John to come into his own, and potentially gives the SIIs another leader instead of a replacement. John is a good person and the Spartans still need him. And if we do want to change anything we'll need all the help we can get.