Hyundai's reasoning for dropping the Azera model is that other Hyundai models, as well as the current crop of Genesis cars, are becoming more widely appealing. So, basically, the narrow range of consumers that demanded a larger, more "luxurious" vehicle than the Sonata, but weren't willing to make the small jump to a Genesis, is too small to keep the model around.
There are a couple of other noteworthy changes in the 2018 Hyundai lineup. The new Accent sedan is still on its way to dealerships, but the Accent hatchback is gone. Since the company hasn't shown an Accent hatch yet, we're not completely surprised by its omission. What is odd is that there's no hint in Hyundai's wording at it being introduced at a later date. Despite that, there's still the possibility Hyundai will simply introduce a hatchback version later, as it did with the Elantra and Elantra GT. And perhaps, in the vein of that i30-based Elantra GT, the Accent hatch could be based on the i20 this time.
Speaking of hatchbacks, the Veloster won't have a 2018 model year. Instead, the 2017 model year has been extended through 2018. We of course know that the Veloster isn't going away permanently, since we've seen spy photos of new versions. So we suspect that this long model year indicates that we'll see the new Veloster by the end of this year, or possibly the start of 2018, with a launch a few months after for the 2019 model year.