While 40,000+ may or may not happen I do think you're probably right that this will be the biggest crowd of Bison fans ever at a single event. Judging from the ticket map it looks likes the first deck is gone except for a few sections by the "outfield endzone" and then the crappy seats up the right field line that face the Bison sideline. The entire Legends club (lettered sections) are gone and a good chunk of the 2nd deck (orange sections) are gone. Here's a screen cap:
Not bad for a game 10 months away still.