To answer the question, which I felt was a very fair one in itself, I believe some of our future legends will include:
Bernadette Peters
Nathan Lane
Audra McDonald
Harvey Fierstein
Possibly:
Brian Stokes Mitchell
Kristin Chenoweth
Gary Beach (if he gets the right part coming his way)
Hopefully:
Brian D'Arcy James
BSoBW2: I punched Sondheim in the face after I saw Wicked and said, "Why couldn't you write like that!?"