1. If Sondheim had written Wicked, it would have stayed true to the book. There would have been no happy ending. Everyone would have died (including Glinda, write at the moment where she has her self-discovery), there would be not one hummable tune, it would be a four hour show (He's staying true to the book, remember?), Bernadette Peters or Donna Murphy would have been Elphaba, while William Perry, Chris Groenendal, and Robert Westenberg would have been in the cast, somewhere. It would have been directed by James LaPine, who would have also written the book, and there would be no choreography. Also, it would have won the Tony, and would have closed a month later.
2. If Rodgers and Hammerstein had written Rent, well, Hammerstein would have taken the project on his own, rewriting the lyrics to Puccini's La Boheme, yet using the same music, because he so enjoyed doing the same thing with Carmen Jones.
3. If Larson had written Ragtime, the score would be modernized, much like Wildhorn. The chorus would have been made up of six people, all doubling roles. And it would begin to snow when Sarah dies.
4. If ALW had written The Producers, the whole score would have been wriiten to the tune of his other show "Jeeves", being that no one saw it, how could anyone know?
5. If Loewe and Lerner had written Cabaret, the MC would have been very conservative, and all of the tunes would be memorable and catchy, not to mention, Julie Andrews would have played Sally Bowles.
Okay - What if...
Jason Robert Brown had written Aida?
Ahrens and Flaherty had written Cats?
Menken and Ashman had written Les Miserables?
"Do you know what pledge time is, Andrew"? said the PBS Executive.
"Yes", Lloyd Webber replied. "My 50th birthday special must be one program that gets done a lot."
"No", mused the man from PBS heedlessy. "Not so much. Our Stephen Sondheim Carnegie Hall concert. That's a big one."
Spoons, forks and knives seemed suddenly to suspend their motion in horror, all around the table.