That's what David Freddoso thinks. Give it a read, this primary season is shaping up to simply be the best...primary...ever. At least for historical purposes.
As many others have said, Freddoso believes that a lot of the Huckabee vote in the South (and Giuliani vote overall) hinge on how well Fred Thompson does in South Carolina.
Also, as Freddoso points out, money may become a factor if this becomes a total national slugfest. This is where Romney's ability to self-finance and raise funds will come into play, as he will be able to sustain himself much longer than most of the other candidates.
I haven't seen fundraising numbers for Huckabee or McCain, but I do know that Giuliani is in trouble (asking for campaign workers to voluntarily stop receiving paychecks), and Fred Thompson's fundraising has picked up to the point that current fundraising challenges have had their limits increase due to the fact that donations have picked up recently.