It is highly unlikely even impossible that any couple would not be able to find a priest or deacon licensed by their local bishop to perform their weddings. 
In the unlikely event which you depict, as SSPX priests do not celebrate the Novus Ordo Mass any couple who did not want a Usus Antiquior Mass would have to have one or do without.
Having said that, I have never heard of any couple married before an SSPX priest having to remarry. So it seems that the Pope is really not altering the status quo.