While I think that may be on the horizon, I wouldn't lose my head over it.
That's not what the school or the experience is about to me. Southerners, for whatever reason, have a really hard time dealing with change. I don't quite understand that. Often, change is for the better, and maybe if we didn't resist change so much Mississippi wouldn't be 50th in the US in so many areas.
If it's deemed best we change our name to the Black Bears, then that's what we'll do, and I will be fine with that. I'm for anything that helps out the university. If we were really so concerned with tradition, we'd demand to be changed back to the Flood immediately, and you'd demand to go back to being the Aggies or the Maroons. Do you think your alums at the time threw a fit when you changed from Aggies/Maroons to officially being the Bulldogs?
I could see Rebels eventually changing if the mascot change doesn't help change the identity of the nickname. And if it does have to change, it has to change, and we'll move on and still be the same university we were before.
On that note, I really doubt "Ole Miss" will ever have to change. The issue with the imagery is its connotation in current society. Many of the SEC nicknames and mascots have Confederate origins (LSU for example), but people don't think Confederacy when they see or hear Tigers. The same can be said for "Ole Miss". People see or hear that, and they think of the university. "Rebels" is another story, which is why I could see it having to change at some point if the connotation doesn't eventually shift for people.