An Amazon pre-order page listing the Nvidia Shield TV Pro popped up earlier this morning and was promptly taken down. The page listed specs of the Shield TV Pro, which largely mirror those of the standard Shield TV. However, the Pro model will use Nvidia's Tegra X1+ SoC and will support Dolby Vision HDR.
https://www.notebookcheck.net/Nvidia-Shield-TV-Pro-appears-on-Amazon-pre-order-page-listed-at-200.439781.0.html