Yep, I've been a fan of the saddle brown interior idea ever since I saw it on the Lincoln MKS about 5 years ago. I really like the look of it on the Infiniti M as well (too bad it's not available with Sport package).
The Cadillac ATS, BMW 3-series, and Audi A4/S4 all offer a caramel brown or a saddle brown similar color option for their interiors...
Again, my thinking is that there's a upscale luxury quality that's attributed to brown interiors for cars in this class and with Infiniti's sedan lineup being down to just two, I wouldn't be surprised again if the brown interior remains carried exclusively onto the M/Q70.
Side note: The new IS350, 3-Series, and ATS also offer red seats are available options as well--which is something I really think would look great with the Q50.