Two weeks later and Costco's TV department at Hayden is even MORE insistent that you MUST buy a Directv package from them in order to watch 4k UHD content. Of course, this still isn't true
See the November 2015 issue of Consumer Reports about new TVs and UHD. There is no mention of Directv or any other satellite provider being needed. You DO need good internet service. This doesn't mean fiber optic service. Netflix claims only 15Mps is needed for their UHD service. Even Centurylink DSL has plans capable of those speeds.
Another good explanation of how to get 4k service is here: http://goo.gl/okiFSG. It also makes NO mention of Directv or satellite.
A good test is to ask the Costco salesperson if Directv can stream 4k content without an internet connection. The answer is NO. If you have a Smart TV (all 4k TVs are Smart TVs) and a good internet connection, you already have almost every 4k show available to watch from Amazon, Netflix and others. Retina display Apple computers are essentially 4k. You don't hear Apple telling you MUST buy a Directv package to watch a 4K TV show or movie on your computer.
My next TV will come from Amazon Prime, not the North Scottsdale Costco.