Sorry, I think you are wrong, somewhat. All the Thompson voters didn’t go to McCain when he dropped out. The difference here would be that Huckabee would endorse McCain so a lot may follow his advice.
The real shame is that Huckabee caught on before Iowa. Without that, Romney wins Iowa over Thompson, the Wyoming win is then more meaningful and less easily dismissed and so New Hampshire becomes a whole new election where Mitt probably wins.
Without Huckabee, I think it more likely that Thompson would have won Iowa, and South Carolina and possibly Wyoming. He would have probably taken Florida and he would be the "inevitable" candidate now.