With what they have, they'd be dumb to not start Ttrubisky. Ride that turd to a smear. Run him retarded. Let Nick clean up late. Foles can't go 16. Save him. Bears' D is gonna be top 5. Mitch has like a 134 average rating against Detroit. They'd be fools to start Foles.
Foles may read shit better, but Trubisky is a far superior athlete, and can do it with a competent o-line, run game, and coaching.
Given what the bears currently have, which isn't ideal, I would start Trubs, give hime the greem light to run AND throw it downfield, and then go to Foles if/when he fails. But I would go hard Trubisky early. Let it loose.