Rueben Mayes

so, it appears to be up in the air right now...

https://heavy.com/sports/2019/10/chi...sky-practices/

out of that article found at the link above, I tried to retrieve the most relevant information(which is vague and non-committal at this point as far as who the starter will be)
"While Nagy was non-committal regarding whether or not Trubisky would start, he did say that his QB1 threw the ball for the first time since getting injured in Week 4. Nagy said he thought Trubisky “looked good,” although his comments seemed to be a good sign for the Bears.

Bears HC Matt Nagy on Mitch Trubisky throwing at Monday's practice: "I thought he looked good."

…Nagy won't commit to Trubisky playing vs. Saints. But if he looks good and there's no setback, there's every reason to expect MT10 will start.

— Rich Campbell (@Rich_Campbell) October 14, 2019

The Bears will face a very tough 5-1 Saints team, and Trubisky still deserves the rest of the season to progress and show what he’s got. Nagy also noted that if Trubisky does start against the Saints Sunday, the quarterback will be game-ready. “You can’t tell somebody to be game ready and not get hit,” he said.

Matt Nagy says that if Mitch Trubisky is cleared to play, then he’s going to be ready to take a hit: "You can’t tell somebody to play a game and not get hit.” #Bears

— Adam Hoge (@AdamHoge) October 14, 2019"

Rueben