The following is only hypothetical, but based on the worsening geopolitical climate, and the trend of nation states moving towards xenophobic foreign policies, I think it’s at least plausible:

A timeline for complete withdrawal of the US from the European Union:

June 6th, 2017 - A day which shall live infamously - Amidst a renewed fervency of patriotism, and in an effort to boost flagging ratings, Bill O’Reilly is called upon by Fox News to examine the question of whether or not the United States should completely withdraw from the European Union. Liberal guest and Professor of Humanities Gavin R. Anola is caught off guard by the proposal and is unable to come up with a single coherent benefit that the US derives from membership in the EU.

Conservative commentator and human leaf blower Ann Coulter is designated winner of the debate after reminding the audience that France is also in the EU, and the French are known to be “Cheese eating surrender monkeys”. Coulter also happens to be pitching her book entitled “The French are a Bunch of Cheese Eating Surrender Monkeys”. Professor Anola is shouted down and leaves the show in tears. Ratings for this show are the highest ever. The question of splitting from the EU fires the imagination of the average American for the first time.

June 7th, 2017 - @realDonaldTrump tweets “BIG THINGS happening. Time to get out of E. U. like Obama never could! We bailed them out of WW 2 and what have they done for us? #USexit”

June 8th 2017 - Huffington Post runs an article entitled “"Dear Facebook friends who voted for Trump: Seriously, why are you so goddamned dumb?”.

50% of America instantly doubles down on #USexit purely out of spite. Ad revenues on both sides are through the roof.

June 10th 2017 - The first #USexit ads launch, and are almost immediately pulled when it is realized that http://USexit.com is already taken, by a pornographic website dedicated to people having sex in Uhaul moving trucks.

June 11th 2017 - http://TheRealUSexit.com is launched, initializing what will soon become the single most polarizing ad campaign in history. Proponents of USexit claim it will fix everything from bringing back coal mining jobs to finally sticking it to The French and The Mexicans. Opponents of the movement have their palms seemingly permanently affixed to their foreheads.

June 12th 2017 - Americans wake up to learn that in the wee hours of the morning, the GOP controlled Senate voted along party lines to implement #USexit, and also to eliminate taxes for those earning $2 million or more per year. Senator John McCain, a vocal opponent of #Usexit and the last remaining hope of Liberal Facebook users everywhere, casts the deciding vote in favor, toeing the party line like the little bitch he is.

June 13th 2017 - #USexit heads to the House. Nobody reads it, it passes. The rest of the world looks on in stunned silence.

June 14th, 2017 - President Donald J. Trump signs # Usexit into law. The law imposes a grace period of 60 days for the United States to clean up any loose ends in the relationship. For all intents and purposes, the United States of America is now completely free of the obligations of EU membership.

The Aftermath

In the ensuing months and years, Americans gradually come to forget all about the European Union. A non-profit think tank adds up the total cost of #USexit and determines that lawmakers spent enough money on it that every single person in America could have gotten “a new Goddamn Hyundai”. When asked if it was worth it, the average American replied “"Isn't the EU one of those countries in Africa, you know, over by Mexico?” Liberals just silently shake their heads and cry a little every night.