The BBC article, which was published Monday 20th June, assesses the arguments advanced by both the Leave and the Remain campaigns regarding the changes that a Brexit could generate.
While the Remain campaign and most experts consulted by the BBC consider that there will be no immediate changes and that long-term changes are bound to be minimal and take up to 10 years to unfold, Leave campaigners have suggested the possibility of adopting an Australian-like migration policy almost with immediate effect, which would lead to a UK-EU relationship that would not include any measures ensuring the free movement of workers.
Discussing this particular proposal by the Leave campaign, Dr Albert Sanchez-Graells is quoted expressing the view that "Giving up on the requirement for the free movement of people while maintaining access to the internal market for UK goods, services and capital would put too much pressure on the continuity of the European project ... because other Member States might be interested" in a similar agreement.
See BBC Mundo for the full article (in Spanish).