Actually that would just be "keeping up with the Jones" with Prime Video. Amazon's video service allows you to subscribe to other services - Britbox, HBO, etc. through just one interface. It is kind of like Apple's 'single sign on', only using one account that you are already signed into.I read some posts that attempted to predict what Apple is trying to "pull off" with its streaming video service. Seemed to be agreement that Apple wanted to be the one-search, one-click interface for video choice, meaning a user would search for "House, MD" on the Apple interface, and Apple would offer up a play button without the user (necessarily) knowing which service provides the stream.
This would gut Netflix, which has worked to build a brand and acquire media to serve. Not sure it would matter as much to Amazon, which provides "Prime Video" as a side-benefit,
Similarly with the FIre Replay box, its guide puts OTA TV content in the same guide as other stuff you have access to. Tivo is similar with their new interface.
The TV app on iOS and macOS will get upsides, but the synergies for AppleTV will be much higher. That is a move to an interface that is oriented more directly over the shows than the channels. (As Netflix is skewed their focus into creating content, they have been shifting into becoming a channel and away from the shows without a channel. )
Roku is even more deeply entrenched in channels, as pragmatically, that is what their apps are called. They, too, are incrementally working to un-silo stuff a bit.... but it would be very different than Roku, which, while providing some ability to search out titles, then links to the streaming service app rather than trying to subsume "Netflix" or "Amazon" et al inside a Roku app.
As long as Apple doesn't hamstring "single sign on" (and/or make it easy to enter account info just once), that really shouldn't be much of a problem. As much as folks want to break up channel bundling into 100% a la carte, that is probably not going to happen. Even if you chop all the programming into 10,000 individual pieces, you'll still need an organizer to hold all that stuff - 1 or 2 organizers, because all of it isn't going to land in just one container (the same forces that brought bundling aren't going to go away completely).It would likely also "hurt" those streaming services which aren't willing to share sign-up and subscription revenue with Apple, as linking a Netflix account that's not signed up through Apple would surely be more cumbersome than linking accounts paid through Apple.
Keeping track of multiple accounts is no harder than what a password manager does. Signing up through Apple or not, they'd be using the same service API to get the index of shows/content. Billing for your account and your account aren't the same thing (even in signing up through the system that Apple runs).
The problem is more for folks who offer the same content as Apple offers for buy/rent/stream. If there are redundant sources, and it is harder (jump to browser, click and sign up) versus TouchID/FaceID with Apple, then that is a problem. If your service is the only way into a show that folks really want to watch, that overhead is probably not a problem (except for the somewhat chronically lazy).
I think Netflix's problem is more akin to the problem Amazon is running into of piling way too much stuff into a single subscription. That is just bundling, with different flavored icing spread on top. If you bundle up way too much stuff, then some folks will start to question where is the money going (even more, if costs steadily creep up).