They won't upgrade because the KU alumni that have money either don't give a crap about football or they give it all to basketball.
They can blame it on the various AD's, presidents, coaches, or whoever, but they have not, and will not, make that kind of investment because KU Basketball will demand it's pound of flesh first.
Can you imagine KU putting forward $160 million towards a football stadium like we have? Of course they wouldn't. If they could actually generate that kind of capital for these kinds of projects, which they never have, a huge chunk would go to something inside or affixed to AFH.