ORD is my home base. I wouldn't book a 50 minute connection time and I don't have the consideration of a wheelchair. Good summary above on the potential/likely gate situations but even if flights are on time doing an E to C connection with a wheelchair would seem really tight. Given that it doesn't take much in the way of irrops to delay you 10-15 minutes, I think that's probably the only real buffer you have to work with. The positive mitigating factor of it being an early AM arrival which means hopefully whatever ~6AM flight was supposed to push off that gate will likely be gone (and the gate will be open) just given that fewer things can generally go wrong with those first flights of the day.