Finally some good news! I’ve been waiting for quite a while for such a ruling.
Edit: Seems this cites an article from 2012, I didn’t notice that (and it’s still news to me). Though there’s still hope that it’ll happen, EU is slow, but usually eventually gets shit done.
Steam would likely still get paid, but there’s no reason they would have to give the publisher anything.
They would if they want to keep the publisher happy. Otherwise the publisher would just see it as losing sales.