At the very least expect to fly...I've logged three instances of being booked on UA (because of better scheduling on the inbound ORD) but ended up buying a oneway on CO because UA cancelled yet CO/Express Jet were still flying.
Typical ORD.

I don't mind the RJ, heck out of CLE you can find yourself on 2-3hr hops in one, so CLE-ORD isn't that bad. But that segment is so competitve I'll go UA for a mainline aircraft with the Channel 9 Air Traffic Control channel.