I do love it when I get to school my one time Economics teacher Sammy Wilson especially when it is about economics. When I read that Sammy Wilson (my teacher for the final term of 1986-7) said Loyalists were applying for Irish passports due to Brexit scare stories I had to laugh.
Sammy should know all about cost benefit analysis especially when it comes to "opportunity cost". In economics this is the value of the next-highest-valued alternative use of that resource. In this case it the cost of time on travelling on holiday. Everyone born on the island of Ireland is entitled to apply for an Irish Passport and the Good Friday Agreement allows everyone in the Northern Ireland to identify as British, Irish or Both. So there is no need for loyalists to renounce their British citizenship to get and Irish Passport.
The other thing to look at then is what people in Northern Ireland use their passport for. As photographic ID to get on flights to the rest of the UK. The UK has promised that the UK/Ireland agreement on freedom of movement will not be changed post Brexit and neither have the Irish who also want a frictionless border.
Next there is holiday flights, most short haul locations that are popular would be in the EU so there is an potential opportunity benefit in being able to go through the EU passport holders queue rather than the non-EU queue. I once had to bring a group of largely non-EU residents into the country at Dover. I whizzed straight through but as the leader of the group hung around in case there was any issues with the members of the group, all but one of the other leaders also being non-EU. I was there long after the majority of EU passengers were safely on their way. Post Brexit going to Spain, Greece, Amsterdam of anywhere else will see more scrutiny of an UK passport or at least be in a queue with people who face more scrutiny no matter what the best outcome is.
Finally there is longer-haul flights and in recent times with the improved road to Dublin and the express bus from Belfast to Dublin Airport a lot more people in Northern Ireland will fly from Dublin to America that maybe catching a flight to London and transferring. So having an Irish passport at Dublin Airport would be a breeze.
Sammy Wilson, the DUP and their Conservative friends have yet to give firm answers as to what will happen post Brexit so many people are looking at it objectively. The costs of having an Irish passport instead of a British one are negligible in monetary terms, but the benefits in terms of time outweigh any additional cost. Therefore it is economically opportune to take up an Irish passport ahead of Brexit, if things aren't worse afterwards they can always get a British one when it is time to renew but that will be based on experience rather than promising utopia in all things post-Brexit. As no matter how much Sammy et al are in cloud cuckoo land about Brexit not everything will be as it is now.