Gore winning the Democratic nomination is difficult but not impossible IMHO, he was a favourite of centrist party insiders when it looked like Clinton might be sunk by the 'bimbo eruptions'. Harkin is not a bad choice for VP; apart from some very minor controversy over whether or not he had misrepresented his naval service*, what stops him from getting onto the ticket? Being an agricultural state ethanol 'porker'?
Bush dumping Quayle is a distinct possibility.
But veep nominee Rumsfeld? I can't see that happening, he'd been out of government so long, he had very little profile by '92. When he was chosen as SecDef in 2001 it was a real surprise to political observers.
*A fighter pilot in the sixties, he flew combat air patrols over Cuba right after the missile crisis. Later on, as an anti-war activist, he'd spoken of flying CAPs over unnamed territory, giving the impression he might have fought in the Vietnam War (he didn't). I first heard of this around 2000 when I read a Rightwing Australian correspondent in the US write, IIRC, "Harkin used to tell people at cocktail parties he'd strafed Hanoi, when in fact all he ever did was shuttle damaged fighters for repair in Japan." This sounds like a gross embellishment of the man's supposed faux pas, and was such a baldfaced lie (I've looked for confirmation of this claim online, and all I can find is the fact Sen Barry Goldwater was upset at Harkin for not clarifying his service in Cuba vis-à-vis Southeast Asia), that it was too much even for the sewer of Ineternet 2.0...