You have a point. But on the other hand, the coaltion of the loser party is much much more fragile than GOP. The loser party consists of a variety of interest group, ethnic minority groups such as labour, women, blacks, hispanics, Asians... There’s far deeper conflict among those groups than the groups within GOP. Hispanic and Asian Americans simply do not like black candidates, and they will not vote for Obama, period.
Don’t forget in the past, Reagan democrats abandoned the loser party in droves.
It always has. But it's a coalition of segments united in their rabid hatred of the GOP. So if Obama is nominated I can still see them uniting behind him more than I can see them flocking to McCain. If Clinton snags the nomination, however, all bets are off. I can see blacks avoiding the polls in droves.