Probably should add A&M's 83k (official capacity, theyve brought 90k in there before) stadium as well. And they've got big improvements to that planned too.
When Ark. joined the SEC, they expanded their stadium capacity considerably. If Mizzou feels the need is there (they averaged 64K in attendence last year), they'll probably do the same thing with the additional resources.
Either way, I don't see it as much of an issue.
(BTW...you were right! It seems the Rock M IS counted in the overall seating...my mistake. I learned something today!)