Will Newt fight on to the convention? Will he continue attacking Romney, or will he back off? What are the incentives at play here?
As Ed Kilgore notes, party leaders will presumably now lean on the disgraced former Speaker to "get out of the race—or at a minimum, to play nice." Will he listen? Especially if, as Steve Kornacki argues, at least part of the whole point of his candidacy is to sell more books (and movies, and lectures, and whatever else he can come up with).
One set of questions here is whether GOP leaders would really be willing to threaten to cut Newt off from the institutions that combine to produce conservative respectability, and whether they have the clout to do so. I don't really know the answers to that, but I suspect they mostly can't or won't. It's almost certainly a solid marketing move by Newt, Inc. to attempt to grab the title of The Conservative Leader...and even if those portions of the GOP that care a lot about winning elections may wind up upset with him, those portions which care most about purity and full expressions of conservative "ideas" are going to be very happy with him. It's almost certainly win-win, too: if Romney loses conservative purists will claim that it was because he wasn't conservative enough (and Newt can cash in) while if Romney wins then conservatives will complain that he's betraying them with his moderate policies. And Newt can cash in. (Not saying that Romney will attempt to be a moderate in office, but conservative purists will naturally be disappointed in the results because purists on both sides are always disappointed in the results and almost always blame the president).
Another issue, however, is about market sizes. Remember, you need an enormous number of votes to be elected President of the United States, and quite a few votes to be nominated for that office. But you can make a very good living off of a fairly small number of dupes, as long as they're rich enough and willing to keep shelling out for every new product you come up with.
So all in all I'm not really sure where Newt's incentives lie, other than to say that I'm quite certain that he really, really knows his marks and what works with them.