Things can change a lot though with momentum. You’d expect Cruz and Rubio to rise in NH and Trump to fall. We just don’t know how much. We also know, as Nate Silver pointed out, that if Trump underperformed his polling in IA, his polling in NH is also probably overestimating his support.
Then there’s the last minute voters. They went big for Rubio and Cruz. The kinds of voters who make last minute decisions in NH are likely to go for Rubio, Kasich, and Christie, so I’d expect all three could overperform.
So basically my predictions are trying to extrapolate from where we are now. Kasich is the #1 establishment guy in NH. So if Trump falters and Cruz just isn’t right for NH voters, then Kasich is best positioned to win.
Waiting for the first post-IA New Hampshire poll is taking the easy way.