Quickest way to get it to happen would be an Open Letter in the NYTIMES, signed by Stephen Sondheim, Andrew Lloyd Webber, Cameron Mackintosh, Angela Lansbury, Tim Rice, John Kander, Charles Strouse, Sheldon Harnick, Scott Rudin, Jeffrey Seller, Lin-Manuel Miranda, Jason Robert Brown, Susan Stroman, and other key members of the theatre community who knew and revered Hal.
The decision would happen in a weekend.
A civilian letter-writing campaign or petition, while well-meaning, is not going to get anywhere. It would need to come from the top of our industry.