It may surprise you, but I have somewhat of an acerbic personality. If I find someone I don't like (admittedly not a hard task), I have the tendency to be as comforting as a syringe wrapped in porcupine quills. My first year in Kansas, I met someone that I despised but was forced to continually interact with. So me being me, I would needle him. We'll call him Mike. At a Halloween party that year, Mike finally decided he'd had enough. He walked up to me in the kitchen and challenged me to a fight.
My initial response was laughter because, once more, I'm an asshole. This took a considerable amount of wind out of his sails. He seemed hurt when he asked me why I wouldn't fight him, attempting to insinuate that I was somehow afraid of him. Mike is about four inches shorter and probably 25-30 lbs lighter than me. I calmly explained that fighting him was an absolute no-win scenario for me. If I beat him up, that's the expected result and I'm now the guy who beat up someone far tinier than himself. If I lose the fight, I would never hear the end of it. He seemed to grasp this and walked away.
Illinois hasn't scheduled Northern Illinois as a football opponent since 2010. The two schools only played a whopping three times prior to that match-up, with the Illini taking all four. It does seem odd that they've played so few times, but why would Illinois want to schedule the Huskies in the upcoming future? Ignoring the fact that Illinois' dance card is full through 2018, it's a no-win gambit for Mike Thomas and company.
By the time both schools can actually play each other again, we have no idea who will be coaching either squad. We don't know if either will be regularly bowl eligible or perennial cellar dwellers or that nebulous space between. But right now, it's nothing more than an empty challenge that Illinois can't really win for answering. It's a rigged game, but you can't lose if you don't play.