Hey, I'll take advantage of this price for as long as I can. Bob Iger sees this streaming service as his legacy (as if the acquisition of Fox, Star Wars, etc aren't enough) and has set this price to guarantee as many subscribers as possible. The next Disney CEO will crank up the price.
As for the competition, Netflix isn't going anywhere. It just bought a film theater in Los Angeles to guarantee the movies it produces will be Oscar-eligible. In another lifetime the idea of a single company owning the entire cycle from production to theater distribution to home distribution would have been deemed illegal, but we're living in a new Gilded Age that would make Rockefeller, Vanderbilt and Hearst envious.