Jack's comments outline that the "succession plan" was in place for some time, based on end of season conversations between Jack and Muffet ("if you were run over by a bus tomorrow"). I find it impossible to believe that Muffet would not have let her assistants know that Niele was "the chosen one." I think pretty much everyone on this board, if asked to chose whether Beth or Niele would succeed Muffet, would logically have picked Niele. To suggest that Beth was caught off guard seems unlikely.

It is quite possible that Beth was ultimately caught off guard by Muffet's announcement, thinking that there was no way Muffet would go out after such a disappointing season. But even then, why would Beth think she would be head coach? To me, it presumes that Niele and Beth must have very different opinions as to how things should be run, to the point where either Beth couuldn't work for Niele or Niele didn't want to try it out.

One other possibility: Niele knew she wanted CW but feared losing her to a similar position within another program and was forced to accelerate her hiring decision, leaving Beth less time to transiton out of the program?

Assuming there was a position for her at Notre Dame and you would think it might have been discussed with her retirement.

Of course if in your point 1 that Beth was disappointed, she may not want to remain at ND in any capacity