You forget if Va Tech beats Boston College Va Tech gets an auto bid. In your scenario, that would mean Va Tech, Ohio St, and West Virginia with auto bids, all rated higher than Kansas. Both Georgia and Kansas are sitting very pretty right now, at #4 and #5 respectively. The only way I see Kansas getting left out of the party is if Missouri loses on Saturday and drops in front of Kansas. That would fill the Big XII's quota with Oklahoma getting the auto bid and Missouri getting the second bid, leaving Kansas outside looking in, even though they're #5. It's the only way Kansas gets left out.
I think the "top 4" scenario comes into play if you're trying to decide between inserting a #12 Hawaii vs. a #5 Kansas (where the BCS would be obliged to take Hawaii and Kansas would be left out if Kansas were the last available at-large team), not a #5 Kansas vs. a #6 Missouri.