Infiniti has largely abandoned flagships sedan since the Q45 was phased out in 2006. The company still offers the Q70L but that's more of a competitor to the Cadillac CT6 than proper flagships from Audi, BMW, and Mercedes.
The company has flirted with the idea of a new flagship in the past and the automaker introduced the stylish Q80 Inspiration concept at the Paris Motor Show in 2014. While three years have passed since that concept was unveiled, Infiniti's head of design, Alfonso Albaisa, suggested the company could have a surprise for 2018 North American International Auto Show.
Speaking to Car&Driver, Albaisa said “In Detroit, we will show something about that subject [flagship sedans] which is super nice." The designer went on to suggest the car will be a "sexy" sedan that has a "new proportion because of new technologies."
That's not much to go on but it sure sounds like Infiniti is preparing to introduce a new concept that could preview a flagship sedan. Albaisa's mention of technology is also interesting as it could be a subtle hint that the vehicle might adopt an alternative powertrain such as electricity. This matches up with previous rumors which suggested Infiniti would introduce an electric concept in Detroit with plans for a production model in 2019.