They will be heading to the suburbs. It would be very surprising if they tried to do another spaceship landing in Soldier Field Renovation. It also has the benefit of being the right decision for the city too, a domed stadium will host a Chicago Super Bowl before 2030, and it's going to be super cool, the entire Super Bowl crowd will freeze and find a deep dish pizza place and just be in awe of how well it works. The Chicago Bears should be one of the NFL's Marquee Franchises, they should have a 75000-80000 seat domed stadium for football games and the occasional visit by Beyoncé in the suburbs, and they will have a huge waitlist for tickets once its built.
I don't know what they will do with Soldier Field, this is legitimately a conundrum to me. I don't know if the right decision there is to demolish the monstrosity they built and try to restore the classic field or just demolish the whole thing, that would depend on who might use a 50,000 seat stadium near the lake with no skyboxes. This is a challenge for someone who knows the options better than me to figure out.