It would have still had a bit of juice to it, in my opinion, because Hall and Nash added a lot of the 'cool' factor the NWO had and if you read Bischoff's book, he admits they came up with most all of the ideas for the group (spray painting the letters on people's backs, for example) and there were times when Hogan wasn't around that the group was still drawing huge. That includes the Wolfpac. But it was Hogan's heel turn that glued people to the product and really helped 'complete' the group, and with him being a huge icon and a guy that most could never imagine as a heel after the big Hulkamania run, Sting turning would have never worked as well, especially when you consider that every attempt ever made to turn the Stinger heel has failed. (I haven't watched much of TNA, but people I speak to or things I read all indicate that every attempt to turn Sting heel have failed there as well.)
The leader of the new villainous group being cheered rather than booed would not have been good for the group's credibility, because that's the exact thing that killed it in 2002 when WWE resurrected the storyline.
Imagine if it had been Bret Hart instead of Sting or Hogan, that would have been even worse lol. There were heavy rumors of Bret being the third man at the time, because Bret was negotiating with WCW at the time and most assumed that since Hall and Nash gave off the impression of it being a WWF invasion (despite having to clarify no longer being employed by the WWF at GAB '96 for legal reasons), that their third guy would be another WWF superstar jumping ship as well. Many even have the misconception that it was Bischoff's original plan (it wasn't) before Bret decided to stay in the WWF.
