wow MK as a PCE exclusive? That would have been a seriously game changer! They thought fighters were on their way out and yet they did all those neo geo fighter port? How wrong were they considering that the fighters genre only got bigger and bigger in the following decade!
Well, at best the MK deal would have been a nice foot in the door, but there is a good chance that it wouldn't have made them any money. MK eventually came out on five systems, for Midway/Aklaim/whoever to have made the kind of money they wanted to, the exclusivity fee for NEC would have had to have been HUGE, probably a money loser in itself even if the system really did take off, and there is plenty of reason to suspect that it would't have. Players already would have had to buy a new system but also two new controllers to have enough buttons, but also a multitap. Most MK players are extremely casual and aren't going to drop that kind of bread.
Also, the Mk1 fad brought huge numbers to the Genesis platform for years on, but that was due to other factors. More people already had Genesis, the Genesis was already famous for having better sports games, the Genesis had Sonic. The MK thing really piggybacked on top of that...and it was fragile hype, even then. Only MK1 was better on Genesis, after that the SNES version had all the gory shit the arcade and Genesis versions had. It was too late by that point though and the far uglier Genesis versions stayed the standard because...I think MK fans can't read, maybe?
The hoard of SNK fighters that were eventually released in Japan weren't part of an expensive exclusivity deal. Also, and this isn't mentioned, they were Japanese games. No circa 1992 Japanese executive would have made that MK deal if even it wasn't fiscal suicide. MK doesn't sell in Japan. Its oiled up white trash muscle men ripping each others intensities out. Its (barely) interactive snuff porn, as far removed from Fatal Fury as it from Faces of Death: The Game.