Newt cant win either. He came in forth in mich; he can win one state, but he cant win most of them. Romney wins in head-to-head vs Newt in most states, and Newt polls 3rd nationally.
Also, conservative vote is still split; so long as Newt and Santorum both stay in, Romney wins. But Santorum ran ahead of Newt so no reason for him to drop out before Newt.
IMHO, it all adds up to Romney winning.
Santorum looks to have peaked for now. He lost Michigan which was in his hands. Romney's retaken the lead in most national polls. Rick's been strong in caucuses, less so in primary states.
For me it doesn't matter so much. Santorum and Romney are both establishment types with similar proposals.
I even suspected the establishment helped Santorum rise throughout Feb. to push Newt out. They want to seal his fate with Super Tuesday.
Look at the mess of the Arizona debate of Romney vs. Santorum, this primary season would be even more awful without Newt and we'd all be poorer for him dropping out.