His record of 45-20 averages out to 9-4 each year: he has one 9-4 year, one 12-1 year, and three 8-5 years.
If he were able to convert one loss per year into a win, he'd look drastically better. He'd be 50-15, which would put his WP at 0.77, basically right on par with Holtz. If you distributed that one win evenly across years, he'd have one 10-3 year, one 13-0 year, and three 9-4 years.
I think this is a fairly reasonable expectation for a five year span: one NC or very near NC run (let's call that making the playoffs), one or two other years where we're in a major bowl (let's call that making one of the New Year's Six), and one or two other years where we're in a decent bowl.
Can he do it? If he runs an offense like yesterday, yes, I think this is doable.