Bannon killed Malashenko's wife and daughterMalashenko's wife was among the civilians whom Bannon opened fire upon during that one mission in Russia, since it's the only confirmed case of Americans killing Russian civilians in the game. Unless, of course, Mrs. Malashenko was in one of those apartment blocks that got demolished along the way.
Malashenko didn't die in SeattleIt's a bit of a neat wrap-up to say that Malashenko went to his death at Parker's hands in Seattle; he was clearly written with the intent that we would assume he's responsible for the final Soviet counter-attack against Sawyer's battalion, even with the invasion lost, and it would be a more interesting scenario if he were taken alive as a POW after his forces were annihilated.
The Soviet Union collapses not long after the invasion of America failsNicely bookending the alternate history, increased public awareness and unrest after a giant military failure, combined with their military both depleted and fighting on too many fronts without significant conquests to assimilate into the economy, leads to the Soviet Union dissolving either as an accelerated version of how it did in reality, or due to coup'de'etat and member secession motivated by the idea of a full-scale American counterattack.
Parker and Bannon are natives of SeattleExplains why they were both in Seattle when they were on leave.
Bannon and every soldier of his company recieved the medal of honorIt's given out for actions which go beyond duty. What goes more beyond duty than letting a freaking nuke go off over your heads?