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I think this then goes back to what is possible and what forms of controls could be negotiated and agreed. If there is zero free movement then your scenario above may apply. If the controls are limited and partial, perhaps applying limits on unskilled workers in some way, then certain sectors such as automotive, aerospace, stem and banking, could experience a minor impact perhaps, with other industries relying on unskilled workers being hit hard?

Sure is some ripe looking cherries there

Still too many unknowns.