Let's look at your proposals:
We'd do well to make the move to any of these three...when it comes down to what is most LIKELY, from a practical P.O.V. involving willingness, timing and back-channel connections, I believe Wittingham is the best and likeliest.
Of course, maximum flexibility for Foley (the time and cover to work behind the scenes) would be derived from Meyer announcing his own "retirement" pending season's end. Can't expect (or certainly count on) THAT happening, anymore than Addazio "doing the right thing" and stepping aside (demoting himself) so that Loeffler gets a shot for the season's balance--essentially giving Meyer some flexibility AND another chance to show he hasn't "lost it".
No, I'm thinking this is likely to get messy unless someone (best of all, Meyer himself) reacquires some combination of honor, class and/or cojones.
For Meyer (and/or Addazio), it's more the first two. For Foley, more the last.