While attendance is nice, what will matter WHEN the conferences realign after the current TV deals expire in the mid 2020s is how popular ISU is on a national scale. By this time my guess is popularity will not only be TV ratings. It will also be tied to how many people pay to follow teams in all manners inlcuding TV, road attendance, Yahoo, etc. Thus, having a team that casual fans enjoy watching (thank you CMC), that people talk about (thank you Tom Herman and Ferentz), and a bunch of crazy Cyclone fans tuning in on all media will help.
Because the Big 12 is the most vulnerable we can only hope that 1) the Big 12 finds a way to stay relevant on its own (25% chance), the entirety of the Big 12 get redistributed to the other Power 5 (10% chance), ISU shows it is a better option than a non Big 12 team like Wake Forest (5% chance even though I would argue ISU already is) or ISU is more relevant than at least one and likely two other Big 12 teams (best chance). I hate to root for failure but we need a team other than Kansas to be the perennial doormat of the Big 12 football over the next five to ten years (their basketball brand is too good to ignore if the Big 12 implodes).