It's an intriguing concept, because Gephardt - to defeat Dukakis - poured everything into Iowa and ended up running out of money come New Hampshire. Per Joe Trippi, the master plan Gephardt had was to do a Jimmy Carter and use the Iowa momentum to jump start everything. It did not work. But I'm not sure if Gephardt does that without Dukakis or not. Because Gephardt was an unknown quantity outside the union workers and labor wonks, so he needed something to capture eyeballs and that's why he felt compelled to spend money on that Hyundai TV spot.
Other candidates to consider: Biden. Biden's campaign was sunk by alleged "plagiarism" of Neil Kinnock's speech (side note: can you remember a time when politicians' public integrity mattered so much that "plagiarism" could be enough to derail you?). But the plagiarism claim came from the one speech when Biden did not cite Kinnock, which happened to be filmed, and the video of the speech was found by Dukakis aides and they leaked it to the media. With Duke out, does another team find the tape and leak it? Maybe, maybe not. But just like that you have to put Biden on the table.
Would a fellow Northeastern Duke no longer running make the case for Bill Bradley to throw his hat in the ring? That is, how early does Duke decide not to run? If it's early enough, we would need to add other candidates who decided not to step up. Including, possibly, the white whale of Democratic presidential primaries: Ted Kennedy himself. And that'd upset the apple cart something fierce.
But no matter who the Dems place, Bush still has one ace up his sleeve: Lee Atwater, the Dark Lord of Negative Political Ads, at the height of his creative powers, back by money and minions to do his bidding. If Biden could be derailed by a single plagiarism whispering campaign, picture what Atwater would have done to him? Picture Southern Democrat Gore with his political family baggage and his white gloves wife and how easily Atwater could have made them lose their marbles. Or, for a true horror show, think what Atwater would have done to Ted Kennedy?
For Dems to win in '87, they'd need to neutralize Atwater, bring gobs of money to the fight, make Bush the target and hammer him to pieces, and rally around a single candidate. It's skating uphill.