He'll sign a multi-year deal with Viagra by the end of the day.*
Zero percent chance he is fired.
The Dude Abides
He hired his mistress to be part of the football staff, and then lied to his AD about her. Head football coaches have been fired for less (Mike Price at Alabama).
"Revolution rock, it is a brand new rock. A bad, bad rock, this here revolution rock."
If this is the AD that hired Petrino, they should have known what they were getting when they hired him (i.e. someone who is a bit shady/slimey but manages to stay 1 step ahead of the repercussions). Wouldn't seem right to act surprised now that something slightly unethical has come to light.