What If... the Invisible Girl married the Sub-Mariner?

For the first time, What If? presents a sequel to one of its other stories. Though the question is above is the subject of the story, the actual turning point remains the original (from What If? #1) What if Spider-Man joined the Fantastic Four? In effect, we rejoin a timeline already in progress, which gives us the chance to update some of our conclusions from that old review. Bill Mantlo and Gene Colan are our guides, so nice pedigree. Let's see how they "completed" Roy Thomas' original...

What If Vol.1 #21 (June 1980)
Based on: Changes resulting from distorting Fantastic Four #13-14
The true history: In our timeline, Spider-Man wasn't with the FF when they rescued Sue Storm from Namor. Consequently, she still felt she was needed on the FF and refused Namor's hand in marriage.
Turning point: Still "What if Sue Storm spoke up for Spider-Man?"
Story type: Swingers
Watcher's mood: Disco dancin' tonight!
Altered history: Spider-Man doesn't slum with the FF for long. He's a solo artist, and plays it like a solo artist.
That velcro patch his worst investment ever, Spidey takes off leaving the Fantastic Four without a fourth member. Without Sue's influence, they're more at each others' throats than ever. Johnny takes things too far with Ben, of course, but Reed is losing it, devoured by jealousy. What he doesn't know is that Sue's moved on. Beluga-style.
Yes, she's pregnant with Imperius Rexy and rather happy, though she does miss friends and family. Namor embarks on a mission to invite the FF to the baptism (and underwater, that pretty much means the birth), but Reed and Johnny don't even give him the chance. They attack on sight and he leaves warning them away. Reed then goes to the U.N. and proceeds to frame Namor. He hopes the landbound nations of Earth will go to war with Atlantis on his say-so, but Ben exposes him and in the process, quits the team. Reed and Johnny see no alternative but GENOCIDE.
They attack Atlantis and Reed plants a weapon that slowly turns the Atlanteans into air breathers, which will force them to land to be "absorbed" into the human race. Namor will lose his kingdom, his power and his bride. Except it may also cost Sue and her baby their lives... they're in no condition to swim to shore. Wouldn't you know it, Sue's waters choose this very moment to break. I wonder what kind of mess this creates.
That's Krang and Dorma attending on her, by the way. They're a couple in this timeline. Namor is gonna miss the birth if he doesn't stop fighting with the Human Torch (the good news: his doctor prescribes cool water for his burns). Reed gets to Sue's bedside first and he's... puzzled.
"What has she been eating down here?" Well, Reed, they're not always in the condition you left them in, you grade-A moron. Namor returns to the royal birth chamber with a captured Torch, but it's Sue who deals with Reed.
See Reed? That's why you don't deserve her. Always underestimating her. Can't believe she beat a nerdy rubber band, eh. He realizes he's done wrong, and heads for the "ultra-weapon" to deactivate it. Krang's already dead by its side (Dorma can't catch a break). He deactivates it and saves the Atlantean people, at which point the Torch leaves in a rage, vowing to take his revenge. Reed then witnesses the birth of Namor Junior and though dejected, promises to keep the peace between Atlantis and the surface world.
Books canceled as a result: While Amazing Spider-Man and its spin-offs are assured following his departure from the FF, Fantastic Four itself is now in danger of cancellation. It's probable that Ben and Johnny would have come back, and someone else drafted in, but without Sue, the FF's long term viability is in question. One could imagine the Franklin Richards specials replaced by Baby Subby ones instead. If you're one of those people, Marvel probably has an assistant-editor job for you.
These things happen: Reed and Sue were separated following the birth of Franklin, and divorce was on the books during John Byrne's stint on FF, but she never went back to Namor. Quite the opposite, he got her and Reed back together after that first separation. More recently, she was unable to deny an attraction for the Sub-Mariner, but they're still far from having a baby together.

Next week: What if Doctor Doom had become a hero?
My guess: He wouldn't have scored his own series, and then in the 90s, would have had four, each drawn worse than the next.