"The math seemed so sound..."
The Rationals will be hardest hit by the end of the world. This is because the EMP pulses produced by the nuclear explosions will fry their beloved electronics like a plate of catfish. For the most part, the apocalypse will be a good thing for Rationals’ marriages.
The fact that the Rationals will suffer most from destruction of civilization is ironic when one considers the fact that they caused it. From Pandora, who opened the box, to Einstein, father of the bomb, the Rationals have been trying to destroy civilization from the get go. However, one might argue that civilization wouldn’t even exist if it weren’t for the Rationals. Such people point to Prometheus (who brought fire to mankind) rather than to Pandora (who brought all manner of evil to mankind) as the exemplar of Rationalism. The truth, however, is that NTs view civilization as a line of dominoes where the goal is to make it as long as possible before knocking it over.
Fortunately for everyone, the Rationals will quickly begin to rebuild what they so foolishly destroyed. Unfortunately for everyone, their efforts will be instrumental in finishing the destruction that they started, only now in more spectacular ways.
One might think that the apocalypse would be a time of technological regression. Not so; in fact, technology will instantly bound ahead. Weapons will become cooler and there will be laser guns and “instant cure” medpacks, not to mention really awesome vehicles to drive around in. The reason for this sudden burst of progress?
Being future-oriented, the NT Rationals saw the end in sight and—calmly and without panic—began to put their affairs in order. For some, this meant trying to wrap their life's work up in three weeks. For others, it meant devising an escape plan to get off of time bomb Earth. Still others spent the time gloating about how their plan to destroy the world was coming to fruition at last. The apocalypse will be something of a renaissance of destruction.
At any rate, for all these reasons technology will make a sudden leap forward. The Rationals will walk around with the best weapons, and their personal gadgetry will be regarded as magic by other types.
Overnight, cheap, affordable, handheld laser units will be discovered by an ENTJ Warlord trying to design better mining tools for his business. The units will be put to good use by his death squads. Also, because the road system is now clogged with cars which won’t go thanks to the EMP pulses, Rationals will build anti-grav vehicles, which they will convert into attack bikes. Some fool ENTP Maverick will develop time travel, then build a prehistoric zoo in a risky entrepreneurial venture. When the zoo goes bankrupt, the animals will escape and establish wild, self-sustaining populations. Survivors will domesticate and ride these nightmares, and human beings will again be threatened by horrific creatures from the past: direwolves, tyrannosaurus rex, and the terrible trilobites, which will annihilate the already-shaken oceanic ecosystem. An INTJ Mastermind will build an army of robots, which will revolt and begin to fight the ruling ENTJs for what remains of Earth. Then an INTP Wizard will figure out the key to faster-than-light drive.
Just when humanity thinks it can’t get any worse, the Rationals will leave the planet en masse.
“So long, and thanks for standing in the way of scientific progress for two hundred thousand years!” they yell out the door as they blast off.
Happy and safe, they will never have to worry about fighting zombies or mutants again. No, instead they will fight aliens and robots.
But what of the few brave souls left on Earth? What of the NTPs who procrastinated the preparations till the last moment and didn't make it offworld in time? And what of the INTJs, who probably caused the apocalypse to begin with?
Fortunately for these Rationals, their strategic planning abilities suit them well for survival. Many will have concocted elaborate zombie plans; when the end comes, they will carry them out. Others will engineer the world's best designed bomb shelters and fill them with the necessities of life, namely computers and books. There will be a small hydroponics garden and a reactor throbbing in the basement. Although not as cozy or inviting as a Guardian bunker, the Rational bunker will be more efficiently designed and sustainable.
Naturally, people sneered when the Rationals started digging holes in their yards. “Haha, look at Brainiac over there, digging a bomb shelter because he thinks the world will end.” But who's laughing now? From within their base of operations, the Rationals can contemplate their next move, whatever that may be.
Possibly their next move will be to hold off the waves of zombies lurching towards the door of the bunker. Driven to achieve competence in any skill they undertake, the Rationals will deliberately set themselves to the task of defense. Alas, unlike the Artisans, who effortlessly kill monsters for fun and hence pick up skills quickly, the Rationals will consciously study to improve their technique and hence pick up monster-killing slowly and laboriously. As they struggle to improve their technique, the Rationals will be haunted by their ever-heightening standards, which keep them ever worried that failure is just around the corner. If they backslide or fail to meet their new goals, they will bitterly chasten themselves as they are eaten. However, their slow learning curve will usually not be fatal thanks to the efficacy of the bunker's computerized autodefense systems.
After the apocalypse, the Idealists (like the Rationals) will be few and far between. Thus, while the ratio of Idealists to Rationals will still be about 1:1, the two temperaments will have far less opportunity to bump into each other. To some extent this will be made up for by the fact that Idealists are quite active about seeking out their True Love; the Rationals, by contrast, believe that if the Idealists are so interested in romance, then they might as well do all the work of mate-seeking—it would be inefficient if both parties were to waste precious time on the process. This traditional approach will fail in a post-apocalyptic world. If a Rational wants an Idealist mate, they will have to actively pursue the venture.
Mostly, the Rationals will marry Feeling Artisans. Playful, courageous and kind-hearted, the SFPs are wonderful mates for the remaining NTs. The Artisans will be able to pull their spouse's nose out of their books and teach them to play, something the NTs had previously considered a frivolous waste of time. The Rationals may waste more time on their honeymoon than they had in all the previous years of their life.
As for the SFPs, they will be grateful for the awesome weapons their Rational spouse will lavish upon them. They will take especial joy in patrolling the perimeter of the family laboratory, holding off waves of undead with the latest and greatest tech. The Rationals, for their part, will be glad that they no longer have to deal with the tedious business of monster killing themselves. They will subsequently immerse themselves in the serious business of research—after all, there's lots to do now that all the annoying traditions and regulations that held back scientific progress are gone.
And so the Rationals will set about shaping a new world, or finishing the destruction of the old one, as the case may be. (Not to worry—they have a plan.) Content to play in the rubble of mankind’s former glory, the remaining Rationals will apply themselves to building their skills, reading, and knocking down the few dominoes that are left standing.