wow you're absolutely right! I've been reading so much on the topic lately (just recently I watched a very nice interview with Jill Soloway who also defines as non-binary and would prefer to be referred to as "they/them") - but only in English as you've made me realize.
Seems like theres no consensus on any solution in German, but "sie" is really not a good one :-/
Anyhow, great for Sam Smith. I hope they feel happy and loved and accepted as they are and as they should :)
Finally someone understands my problem and when you Google about this topic, like the Wikipedia article, the Focus is only on the englisch language. And because I know no one that is identifying as non binary I have no one to ask for.