Sure. And have it on by default with a correct content security policy. If it were off by default, it wouldn't be used by most folks and the bandwidth thieves would be content hotlinking images and direct linking binaries, just ignoring the small percentage of users who turned it on.
Of course, even if this was released today and referrers were phased out in June 2014. We'd still be able to use them for at least 5 years until you could safely assume that they were gone. Likely longer.
