Nvidia has narrowed the scope of its Tegra X1 SoC to so few products that the processor has almost no competition to speak of anymore. Nvidia can afford to hold out on a proper successor for longer since the Shield TV console and Nintendo Switch are essentially tied to the Tegra family.
https://www.notebookcheck.net/The-aging-Tegra-X1-why-Nvidia-won-t-let-go-of-its-four-year-old-processor.424910.0.html