Sales simply haven't met expectations.
Hyundai certainly took a chance when it decided to produce the Veloster. It's definitely not the most conventional three-door hatchback out there, but it has quite a unique design that some love while others don't. Still, just 60,000 units were sold globally last year. Just over half of those were for customers in North America. Sales basically declined in 2013, and because of that Hyundai isn't so sure whether to build a second-generation model.
A significant refresh is slated for next year, which will see a redesigned front-end, revised interior, and many other updates. But that refresh may just represent about as far as the Veloster will ever go. Yes, there are the Turbo and Turbo R Spec, but in the face of fierce competition like the VW GTI and the now refreshed Ford Focus ST, neither of those two fare all that well. The Veloster and its hot hatch variants aren't bad cars, it's just that there are better and more established alternatives out there. Hyundai is happy though that the Veloster helped to change public perception of the automaker for the better. No final decision regarding the Veloster's future has been made yet, but unless sales pick up, its future doesn't look so bright.