I have a prediction for 2008:
Romney/McCain vs Hillary/Obama
I could be wrong but potential nominees who debate each other with angry words immediately forget their enmity and join together like best friends in hopes of offering the most powerful ticket.
There is a possibility that Romney & McCain are both too egotistical for either one to settle for "second fiddle", but they might overcome their differences for the common good of the GOP in order to challenge Hillary & Obama.
Obama is too much of an "upstart" to refuse to accept a V.P. position under Hillary. Not to mention he needs the experience first to run for high office and everyone knows it.
Hillary promises to be a great President if you oppose JTF, and would love to see America reduced to the socio-economic status of Brazil or Venezuela. In other words, she stands to garner about 50% of all votes cast come election day. She's also such a vicious loud-mouth & con-artist that it will be next to impossible to defeat her...she'll use every dirty track in the book, and when she starts denouncing Romney & McCain directly to their face as "tired, old, has-been 'white men' with no understanding of diversity and interracial culture", any reciprocal denunciation by her Republican opponents will be branded as "racist" & "nationalist" in the next days' news and on TV. This might well be the most low-class and dirty campaign ever witnessed in all of history. The mass media is going to do to Romney/McCain exactly as they have done to Ron Paul--pretend that they don't exist, and if pressed to admit otherwise, will refuse to give any credibility to their platform and previous record.