I believe a second Bush term will be a disaster for the Republicans in the long term. The country is polarised. Bush will have 'honeymoon' ratings of 60%, which will fall to the 40's before the summer of 2005. I see a Democratic landslide on the cards come 2008 if Bush wins. Also, if Kerry wins, I think he will loose come 2008.
If economists and other commentators are to be believed then Bush's tax cuts of 2001 will leave him with some major economic troubles during a second term. A Bush victory in 2004 could do for the Republicans what Major's 1992 victory did for the Conservatives in Britain, ie. leave the party dogged by an internal ideological struggle (in this case between moderates, eg. McCain, Giuliani etc, and the religious right) and perceived governmental incompetence.
Btw, I agree with Boss Tweed that Edwards/Ford is the Democrats' best ticket for 2008.