Bears Net Value would go through the roof (pun intended) if they built a shine new modern stadium, plain and simple.
We see it everywhere across the country. Malls are being torn down and replaced with other shopping centers. I think the Bears are now in a position to say, we want a new stadium, or we are moving on.
That lease only benefits the Bears, because it will take a few years to develop and build the new location, and when it is ready they will pay what they need to get out of the lease.
A good attorney team for the Bears will likely find some shortcomings of Soldier Field, and the Park Services will simply be out matched in court, resulting in a reduction of the Lease or a complete revocation.