According to Buzzfeed Theresa May insisted on this paragraph.

So while approx 500 million Europeans will be able to wander freely 66M Brits will be denied the same privilege (and guaranteed the difficulties put in place will be strict, time-consuming and annoying)

Millions of young people are going to hate the Oldies (not me ) with a vengeance.

They will be stuck competing for jobs on an island while on the Continent young people can move about freely, discover new opportunities, up stakes if it doesn't work out and go elsewhere...while Brits are still filling in their immigration forms.