Neil Diamond sang in the original key all the way to the end. Paul Stanley of KISS tries.
Of note - one thing I can't hear a lot on Phil's voice is effects. The vocal effects that are used today by artists are sick - above anything we could have ever imagined. A lot more than classic reverb, echo, etc.
Mick Jagger, with some exceptions ("Paint It Black") still handles just about every song in their original key, and his falsetto is very strong even at 78. Paul Stanley is in worse shape vocally than Phil is, in my opinion. Phil at least knows his limitations.