In a little over six years, over 1.3 billion iPhone and Android smartphones have been sold around the world, and all of those devices have access to mapping software. Combine that with the propagation of in-car GPS systems, and it spells a swift demise for the stand-alone GPS units for vehicle dashboards, which saw widespread success in the early and mid-2000s. Since smartphones started offering GPS capabilities in 2008, sales of stand-alone GPS units for vehicles have seen a 15-20 percent decline per year.
Costing between $75 and $350, standalone GPS units built for vehicles from companies like Garmin and TomTom are already losing their viability (although these companies are still finding success with GPS units for boating and other outdoor activities), and will likely be completely removed from the market in five years. As battery technology allows for more usage time in smartphones and more people move into newer cars with built-in GPS systems, opting for a standalone GPS unit will cease be an option in the near future.