I wouldn’t consider it a completely done deal at this point. But note that I also said if you’d already made your site with underscores, it probably wasn’t worth trying to migrate all your urls over to dashes. If you’re starting fresh, I’d still pick dashes.
It’s Not Just Google That Treats Underscores Like Dashes that I wrote a few weeks ago, obviously now needs to be updated.
We will keep you informed of any new changes with this, as we hear updates.