They're here -- the Chicago Fire have released their new secondary jersey for 2017, and you can get your own now via MLSstore.
This year's version is based on light gray, with a new visual texture throughout. Here's the front and back of the men's authentic version:

Here's how it looks with long sleeves:

And here's the women's version:

Here's a look at the texture and details like the club crest and stripes, as modeled by Juninho:

Get your own new 2017 Chicago Fire secondary jersey now via MLSstore.