I only have three main thoughts on the subject:
1) I think we could match whatever Illinois would be willing to offer, but would Currie actually do it? I don't know the answer to that, and I'm not comfortable guessing either.
2) My observation is that Big Ten schools tend to be pretty image conscious. I'm not sure a ranting/raving, f-bomb dropping, arm waving sideline crazy person matches what those schools typically look for in a coach.
3) Illinois isn't a gigantic step up. It has it's advantages, but in the grand scheme of things, a job like Arkansas or NC State would have been a better fit for Frank last year, and he really didn't get a sniff at either (that we knew about). He obviously got locked out at Miami, too.
Honestly, right now, given where Frank is at in his career, he's moving up the list of sought after coaches. However, his personality is going to turn a lot of people off at these 'good' jobs because AD's can get a lot of good coaches without his "Frankness".
He's good enough for an Illinois, but Illinois can get someone that would be less of a potential headache for the same or less money. All things considered, that's what they'll probably do. Just like every other job that's potentially 'better' than KSU.