1. Support musl 2. Become mainstream with musl distros 3. Become dependency in practical terms 4. Then even software optimized for musl-based distros has to deal and support systemd

But do you have any proof for beyond #1? Seems like a far jump here, but maybe I'm missing something obvious.

Nope. It's my view of the situation and I'm confident that will be the case. Not that it's an evil plan. Just a nature taking its course. This is how I see it.