It should definitely feature the work of a multitude of writers and artists, but I will be very sad if Morrison and yes, Mark Waid, are not involved in some way. Same for any and all surviving Superman writers (Maggin, Bates, Stern, Wolfman, and so on) and artists (too many to mention).
The story should be in the vein of Action #850, involving a character traveling through time and space, seeing Superman's exploits across history and across the Multiverse. Maybe Jon Kent becomes dimensionally "unstuck" and travels the Multiverse, seeing multiple histories of multiple Earths that parallel Superman's real-world evolution. The Generations Earth would be the place to see his Golden Age origin, then move to another Earth for the Silver Age, and so forth.
I'd also love to see DC go for a thousand different variant covers. It seems daunting, but this is an epic moment in pop culture and Superman history. Get artists started now, and if there's not enough artists to accomplish the task, do multiple media covers, featuring all the film and TV Supermen (with the exception of Cavill's NotSoSuperman, IMO) and even include animation.
I just hope DC doesn't screw this one up like they did with the 75th anniversary. It had some highlights, but it paled in comparison to what Batman got with his anniversary. He's my second favorite character, but Superman is THE first and greatest superhero and the "All Father" of the genre.