Perhaps there are more informed readers who can comment on the news item that I ran across.
Starting immediately, no new features will be added to the legacy SDK visual screens arena. Creators will be asked to move to the new RSG or Direct Publisher for Roku by July 1st, 2017. On January 1st, 2018, all channel updates will be required to use RSG or Direct Publisher. As of January 1st, 2019, all legacy visual screen components will be removed entirely from Roku OS.
Roku suggests that support for visual screen components that were part of the 2015 SDK will end on January 1st, 2019. That should give developers AMPLE time to make the change on up to the next interface. Developers who do not update to the new platform will likely be removed from Roku at that time.
My interpretation is that unless the Simple.TV Roku app is updated by Jan 1, 2019 it will be removed since it was probably created with the original Roku Software Developers Kit.