The Mexican Government will not give up the profit. BUT the refineries are so inefficient and so outdated their refining costs are probably more than the price of imported fuel If they do allow a truly open market ( not the Mexican way) there will be obstacles for  those that are importing fuel; Safety inspectors will visit weekly, they will test the pumps and if they are off by 3 oz. per gallon the station will be shut down Mysteriously the power will go off regularly.  The Unions will complain and there will be strikes. This is what Mexico did to Costco when they arrived in Mexico. They fined them for scales that were off. Meanwhile Ley's was using balance scales that were 50 years old! Today's paper had an article on how gasoline will return to steady increases in 2017. BUT tit does appear that ULSD will be available in the near future.
Moisheh