I don't think you understand how much content they have. Star Wars + Marvel is over 30 movies. How much free time do you have?
At 1 movie per day that's $6.99 to watch them all in a month (that is, if I hadn't seen most of them already - see below). Where's the incentive to keep me subscribed?
Disney has said that they are ending their “Vault” program. All old Disney content will be on Disney + (except Song of the South).
I am pretty sure content will not be like Netflix where they release all episodes in a season at once.
You also need to realize that Disney is very massive. It’s not just Marvel and Star Wars. Not only will they have new content, but they will also have their entire archive dating way back. And it’d be even bigger when they get Fox content as well.
And? What do I care about old content? The majority of that is already available on TV right now in reruns or movies of the week. In the last couple months the following have been on cable TV: All three Iron Man movies, all three Captain America movies, the first two Thor movies, the first five Spider Man movies (all except the newest Tom Holland one), the first Guardians movie, the first two Avengers movies, Doctor Strange and the first Ant Man. So I'm going to subscribe to get what, the latest few movies that aren't yet on TV (but will surely end up on TV next year anyway)?
Old Fox content? So what, I can see Simpsons? Oh wait, they already have umpteen reruns of that show. Can you name me any content on Fox that I either haven't already seen, or isn't available on reruns? And even if they release all the old Disney/Fox content, once people have watched what they're interested in, why would they keep subscribing?
So really the only value in the subscription is new content. Disney has a big advantage with the Marvel and Star Wars franchises to create new content people would be willing to subscribe for. Then again, maybe not. Ask yourself this - if Disney had a really good Marvel story, would they rather make another blockbuster movie and rake in hundreds of millions in ticket sales or would they rather make a "dumbed-down" version and give it to their subscribers (who are already paying, so there's no "extra" money to be made from it)?
Personally I'm starting to get sick of all the streaming services. What I wanted to see (and hoped Apple would do, but knew it wouldn't be possible) is to have an iTunes version of TV. Let me watch what I want when I want without having to buy "bundles".
But that possibility is moving father and farther away. Everybody wants their piece of the streaming service pie. And there's no way in hell I'm going to subscribe to Netflix, Apple, Disney, Hulu, HBO and Amazon because none of them want to work together and think the secret to making money is keeping all their content to themselves.
I used to hate the cable companies, but they might end up looking like the good guys by offering the most overall content from a single provider.