I turned on my Samsung 3D UHD television this morning. The set had a message to update it's apps. After choosing "all" the "Ultra HD Sampler" app disappeared from my current list plus from "My apps".
I will miss the 4K app since I was one of a few to view everything posted on the app since early 2016. Those who have the app will most likely find it missing. This was the only 4K Comcast supplied "free" since it was included in the monthly price for my level of service.