I used to play for the Illini Hockey ACHA D1 Club team and due to the fact that we were a club, I was exposed to a lot of interaction between the University and our team. That being said I thought I'd share some of that information with you so you all can have a better understanding of the potential for a D1 NCAA hockey program at Illinois.
As a club team, the Illini Hockey program is funded entirely by player fees (about $1500 per player/season) and gate/merchandise sales. The team also has a large number of costs that it must cover in order to play each season including paying the university to staff each game, to rent the ice for each game, to rent the ice for practice 4 times per week, advertising, etc. After all is said and done, the team has been able to turn a profit over the last couple of years, operating on a 6 figure budget, as the popularity of hockey has increased both on Campus and a regional scale (the Blackhawks winning obviously helped).
Even though the club team has operated at a profit and has the third highest game attendance per season of all sports on campus (average 800-1000 per game with an all time high of around 2000), there are still too many things standing in the way for Illinois to field a D1 NCAA hockey team in the near future. Using the current ice rink for a D1 team is not an option due to the fact that the NCAA requires a minimum seating capacity of 4k-5k for all new D1 NCAA hockey teams (seating capacity at the current rink is ~1250) and the rink is not regulation size. Another problem is that while hockey may have proved that it is in demand in C-U, it is pretty far down the list of sports the AD would like to add. Mens swimming and men's soccer are both sports that could be added to the Illinois AD for significantly less money and without having to add new facilities to the university.
In the end the crux of whether or not Illinois ever gets a D1 NCAA hockey program depends on money and Title IX. Penn State would likely never have added a program if their donor hadn't donated upwards of $80 million to cover not only the cost of the new rink but also scholarships for both the men's and women's teams in the early years of the program. I've met a lot of Illinois Hockey alumni and even our most prestigious alumnus (he's an astronaut) hasn't been able to drum up the support needed to create a D1 NCAA program. Sorry for the length and the negative outlook, but I don't see this happening anytime soon.