I do sincerely think this is the case. Not from a standpoint as a NT fan but what I would hope to see if I were a KSU fan replacing your legend of a coach. It comes from a place of watching a team cough up three 20+ leads this year that separated us from going undefeated. When that occurs it isn't narrowed down to one or two plays. That is a collapse.
Not winning bowl games, winning championships and not having a strong reputation of recruiting (until this year) are also factors that would concern me. I would like to see him stay but if he is wanting to go I (personally) can't stop him so it is what it is. I just wouldn't expect a high chance of success for the P5 that takes him until he incubates longer.
People might tend to say "oh well it was North Texas" but remember who we play? Barely beating UTEP and UTSA shows us that something was wrong when our coach can't handle these two bottom-feeders (this year anyway).
If he is gone then Trust in Wren and it's on-wards and upwards.