I also very much doubt he'd be interested in making a change anyway. His team is better already-- and it's not like Chicago treated him all that well.
I suspect you are right, but money usually talks.
Even if he was able to listen to an offer from the Bears, the 49ers would likely step up with a raise and/or extension that would make it unlikely he'd leave.
BTW, Lovie Smith has 1 year left on his contract with the Bears, so he will get paid well for the next year (about $5.5 million).
And, as mentioned, he will almost certainly not have trouble finding another NFL job with his qualifications, and the requirements for NFL teams to hire minorities.