I don't think this debate will change much. Pretty much the same people who always do well did well again. Trump was his usual. Christie and Paul had good nights, but are they really going to get a bump? I doubt it but I wish they would. Cruz and Rubio did well, but I doubt they'll gain ground on Trump.
Right now I have to say that I think Cruz is in a great place. I think in the end if the field narrows down to just Trump vs Cruz then you'll see Cruz continue to garner anti establishment support while also pulling in virtually all of the establishment support. The establishment doesn't like Cruz, but if they're going to vote for a republican they're going to vote for Cruz over Trump. I'm not sure if Rubio can get enough anti establishment support. I think in the end it will come down to those three.
I also think there's an outside chance Paul Ryan gets in the race, especially now that in looks like Trump is the favorite.