I don't even hate systemd but like it, will distro maintainers opt to support "systemd pam" alongside old pam or will they discard it? I use systemd more than when I don't but only because it was forced. I can't use devuan and gentoo everywhere. That's why I prefer fixing/updating pam with a backward compatible replacement so maintenance burden is minimized and everyone is happy.
The problem is, lennart and the systemd folks are not happy with systemd being popular, they want to decimate any competition.
I think their point is that if it's in the default configuration of Ubuntu or red hat, it's "shoved down their throat" because it is on by default and they assume they are made to care about it.
I'm not saying PAM should disappear entirely and nobody should be allowed to use it, I'm saying as someone who happily uses systemd I wouldn't mind/would quite like similar functionality to be part of systemd, and I could stop using PAM.
But if you feel you're forced to use systemd I'm not even saying you should have to use this hypothetical part of it - just like boot, networkd, homed, etc. don't have to be used just because you're using systemd at all.