"Audi has had a long and successful history at NAIAS, debuting countless models that Audi customers enjoy today. For 2019, we have decided that we will not participate in NAIAS. We will continue to evaluate Auto Shows on a case by case basis relative to the timing of our product introductions and the value the show brings from a media and consumer perspective."
While disappointing that the company won't be showing anything at Detroit this year, the good news is that the door is open for a return. The part about evaluating shows individually means that, if they have something they think they should show in Detroit, they'll come back.
With the departure of three major OEMs from the Detroit show, each with sizable displays, it means that there will be a fairly large chunk of real estate up for grabs. Perhaps next year Mitsubishi and Volvo will move back into the main hall, instead of being relegated to the hallways outside. And maybe some other companies, such as Volkswagen, might expand their displays.