I agree. Here in Colorado leases run with the land. That means that a lease is in full force and effect regardless of the ownership of the property. Your Illinois attorney can verify that for your state.

From a practical point of view, you're in a pretty good position. In this market is highly unlikely that anyone would want to lose the existing tenants. Conversions of apartments and condominiums has all but stopped. And any higher and better use would likely require scraping the structure and building something new. Again that's not likely to happen in this market.

You should contact an attorney. Illinois law, 735 ILCS 5/15-1701(h), states,
"Unnamed parties, including tenants, who came into possession before the foreclosure proceedings, cannot have their right to possession terminated by the Order Approving Sale. The Plaintiff must obtain either a Supplemental Order of Possession or file a forcible entry and detainer action. Tenants have no defense to either of these actions, although they may enter an appearance in foreclosure action if they wish."

I would expect that despite the foreclosure, your lease is still good and you should be able to remain in the unit through the remainder of it. The lease is a contract that doesn't get cancelled due to a foreclosure.