Yeah, I can only see this deal right now being beneficial if it's your
only choice due to Apple simply not wanting to host your apps. So, 18+ apps, emulators, various apps banned from the app store over drama (Fortnite).
It's also beneficial if you keep you
1. Keep your install base under 1M. So only if you're sure you have a niche app that you barely need to maintain.
2. If you somehow have a premium popular app. A $2 app would mean Apple is taking a 25% cut, a $5 app is taking 10%. Of course, since this is per device you will probably be hit by users who use multiple devices. Worse yet, apparently the install fee is "first install per year" and includes updates. So you will take a huge revenue dive if you want to maintain, de-incentivizing devs from supporting existing users
3. Manage your own alternative storefront. I feel this is where the deal may start to hit anti-trust issues depending on how the store takes these costs. Apple doesn't have to pay it's own store fee while a new store has to pay Apple for existing. Sounds like a way to suppress competition before it starts.
I guess Epic v Apple part 2 will hit faster than expected.
EDIT: oh, I don't know the logistics, but #4 can be ad supported apps. The most user hostile style of app but potentially one that can keep making it's $0.50 back year after year if they have an engaged user base. But since I know so little about adtech I am happy to be corrected on if this is sustainable