Undertaker was legitimally hurt & decided to drop the title. Mr. Kennedy was in line for a huge push to begin with. However with the injury, there was some talk of making it even faster.
Mr. Kennedy got injured at a house show in Poughkeepsie, NY I believe. His injury was originally supposed to have him out 5-7 months. However it turns out it is not as serious as they originally thought. I'm not sure what they will do now that he won't be out as long as they thought he would.
Obviously something big is going to happen on Smackdown this week. I won't spoil it but it isn't too hard to figure out.