Likely yes, but given this season, watch him get 45% in NH. Nothing would surprise me anymore. Regarding your 2nd point, it looks like it Trump's unlikely voters did show up to caucus for him, but there was also a last minute surge of stop Trump at all costs turnout. Look at what happened to Le Pen's party in the runoff round of French provincial elections. They were shut out by a late surge of anti-racist turnout.
You may be on to something here. It may not be quite as straightforward as "stop Trump at all costs", but you're right that you can't simply explain this as "Trump's voters didn't show up", because then how do you explain the high turnout? A lot more voters than expected
in absolute numbers and not just percentage terms showed up for Cruz and Rubio than we would have predicted before caucus day. It may in fact be that the fact that Trump consistently leads not just the "who would you vote for" polling question but the "who would you never vote for" question means that his presence in the race encourages the supporters of other candidates to show up at the polls.
Poll
