Hilary and Haylie Duff are of course spokespersons for the gum. You've probably seen the commercial where the sisters say the gum is "the frosted cube that is surprisingly cold." Racecar driver Kevin Harvick also endorses Icebreakers.
So will Hershey have to stop selling Icebreakers gum? I doubt it. There will probably be a long court case, and I'm guessing the two companies will reach some kind of agreement. But I'm not a lawyer, so what do I know?

Haylie Duff, Kevin Harvick, Hilary Duff