Don't think it would have any effect at all. People that are already here could stay and still have a right to bring their entire families over.
It could curb a potential increase in frequencies of some existing Luton routes if there was a drop off in new migrants but as the BBC reported 272,000 new immigrants came to settle in the UK in the 12 months to June 2014 from non EU countries where there is suppose to be strict limits which is greater than the EU figure.