Lakeside accounts for 22 percent of the 2.6 million square feet of exhibition space at the convention center. Its 141,000 square feet for things like corporate meetings were used just 33 percent of the time in 2016, much lower than the 50 percent occupancy rate for meetings in McCormick Place's North and South buildings. And demand for Lakeside's entertainment gem, the 4,250-seat Arie Crown Theater, may be largely replaced by the new 10,387-seat Wintrust Arena slated to open this fall.

Yet Lakeside still is a cost-effective option for trade shows with smaller budgets and events that fill hard-to-book gaps in the convention center's calendar. Rent is typically about 50 percent of what shows pay to use McCormick Place's three newer buildings, according to sources familiar with event contracts at the venue.

More important is that Lakeside's exhibition Hall D was used more than half the time in 2016, which is why any answer to the Lakeside Center question requires maintaining or replacing that 300,000 square feet. "There are legacy customers that need Lakeside to accommodate their needs," says Don Welsh, former CEO of tourism bureau Choose Chicago, who booked events for McCormick Place in recent years and favors redeveloping the building to take advantage of its lakefront location.

McPier's most recent pitch to replace the needed space came last year, when it proposed spending about $350 million on a bridge building connecting McCormick Place's South and West facilities. The plan would have been made financially feasible by filmmaker George Lucas, who had promised a huge private investment to build the Lucas Museum of Narrative Art and an adjoining park in place of Lakeside.

That idea was thwarted by a legal challenge to the use of parkland for the museum, a testament to the formidable obstacle that activist groups may pose to any Lakeside Center redevelopment. But the bridge building remains McPier's preferred solution if it can come up with the money to build it. "To keep our campus operational, we have to have (the Lakeside Center)," Healey says. "And until we can figure out a way to pay for that bridge building, we have no choice but to make incremental investments in it."

McPier swung and missed again on a funding solution late last year when Gov. Bruce Rauner vetoed a bill that would have let the agency tack on $293 million to its current long-term expansion debt of $2.6 billion. (Fitch recently downgraded that debt to BBB-, one notch above junk.)

It had proposed using that bond sale to pay off a construction loan for its new 1,206-room Marriott Marquis hotel instead of the current plan, under which the hotel's revenue will pay off the loan. Freeing up hotel revenue would help McPier fund space to replace Lakeside.

Healey says she is tweaking her bond proposal—which passed the Illinois House and Senate last year—to address Rauner's concerns of putting taxpayers on the hook to cover any debt service shortfalls.

Another option for replacing Lakeside Center's useful parts may arise just south of the convention center on 90 acres of land that includes McPier-owned truck yards and the former Michael Reese Hospital site. The city and McPier jointly filed a request for proposal late last year for ideas on how to redevelop the property, which may include addressing McPier's Lakeside Center problem.