My company makes pluggable chat software. I'm sad about this development, because it means that we can't audibly notify users anymore when someone writes a message to them. I wonder whether there's a way around that, but I don't see it.
I've been messing around with the Web Audio API lately and the message Firefox leaves is that it will still work as long as the user initiates the sounds loading, not the page. So if the user opens your chat or maybe interacts with your page in a way that indicates they've given you permission to play sounds then you're good.
So some responsible users are affected by this change, but it is also a necessary change due to too many abusers. This is why we cannot have nice things.