If they put it in the St. James and close the balcony, they end up with a theatre of 1,300-1,400 seats -- that could work just fine. If it turns into a hit, they can always open the balcony later.
The Booth isn't available and neither is the Music Box (at least not before year's end, and I'd be shocked if the Weisslers closed "Pippin" that quickly). I've heard the Nederlander has a show for the Spring that has yet to be announced (a musical revival) so I believe that's not an option either.
"No matter how much you want the part, never let 'em see you sweat." -- Old Dry Idea commercial