Dish believes their 600K subscribers are predominantly cord-cutters or subscribers who have never paid for traditional cable bundles:

“Either they have never had pay-TV because they are 25 years old and it never crossed their mind to have pay-TV,” Mr. Lynch said. “Or, they cut the cord some time in the last one, two, three, four, five years.”

But how is Sling any different than the traditional cable bundles? Yes, Sling is streamed, but the service offering is still a bundle of channels. Let's also not forget that Sling is owned by Dish, a major "traditional satellite/cable operator."