R. Star wrote:
Except... Khan hijacks Reliant and Genesis as normal. But not being able to lure Kirk in since he's behind a desk, he takes Reliant to Earth and uses the Genesis device just to kill Kirk. His reign on the New Terran Empire is glorious but alas short as the planet destabilizes and any escape is impossible due to the arrival of the whale probe. Once Praxis blows up, this leaves the Romulans as the dominant power in the region.
Khan hijacks the Reliant
and sets course for Earth, but Starfleet is tipped off by the lack of contact from the ship, so dispatches a fleet (spread out in a 3D pattern, since Khan apparantly can't adapt to the extra dimension) to intercept and engage the Reliant
. The ship is destroyed light-years away from anywhere, the Genesis Planet isn't formed, David Marcus survives and both he and Saavik remain onboard the Enterprise
when Decker takes it back to 1986 to recover humpback whales.
TFF is just completely forgotten about. Then due to his more enlightened mentality, Decker doesn't start in interstellar incident with the Klingons.