I've been doing some research on portability and systemd but couldn't find
much.
> Is systemd going to be an obstacle when people want to port applications to
GNU Hurd or other Unix-like systems?
Not sure. But this isn't the first time that happens[1]. People simply use
compatibility layers (like Wine) to overcome the lack of portability of the
subsequent programs. It works but sill not ideal as lack of portability is
the sickness and compatibility layers just a placebo.
This is not related with systemd but with portability in general in the free
world. Andy Tanenbaum said this at FOSDEM 2010[2]
It's just amazing how much free software is so crappy, it's not portable. You
know, you run ./configure and it always fails, *ALWAYS*. You know, what
happens? It was looking for, I don't know, Perl 5.2.3.26.9.4b and if that
wasn't there it gives up. Even though the application you're trying to
install doesn't use Perl at all.[2]
[1] https://teythoon.cryptobitch.de/posts/on-portability-of-init-systems/
[2] https://www.youtube.com/watch?v=bx3KuE7UjGA Minute 38:20