I don’t believe it will ever happen but I have to say I’d be open to the idea if it was implemented in the right way. Carr does make some good points in the video and whilst I don’t always agree with everything he says at least he’s putting an opinion out there.
I’m fairly sure some mainland European countries allow purchase of beer and wine at 16, although whether this only in shops or includes bars/pubs as well I don’t know. If anything off sales should be subject to higher limits because as you say there is more oversight in a pub.