When will this be added to Lightroom?
We're not Adobe employees here, we are just Lightroom users.
So the only answer we can give you is ... um ... we don't know when this will be added to Lightroom. We don't even know IF this will ever be added to Lightroom.
Perhaps you should submit a formal feature request. Photoshop Family Customer Community, but even if you do that, you won't find out "when"