#2 No Undertaker or John Cena
With regards to The Undertaker, there are really two ways of looking at it. Most fans will actually be quite relieved about the fact that The Phenom won't be competing at WrestleMania this year.
The reason for this is that he's far past his prime and should have retired years ago. Moreover, his supposed WrestleMania 33 retirement just turned out to be false and he wrestled again on more than one occasion after that.
On two of those three occasions, he further proved why he really shouldn't be performing in the ring anymore. However, the inner fan will be sad that for the first time in 19 years, there will be no Undertaker at WrestleMania.
As for John Cena, it's possible that he has a match as well, but from the look of things, he's really nowhere to be seen at the moment. His busy schedule may make him miss WrestleMania again.