James Pindell gets a bit ahead of himself:

If the Republican race were immediately to become a two-person contest between Trump and someone else, it is logical to assume that the other person would have more support.

That would be true if most current non-Trump supporters would all rally behind the other candidate, but there is some evidence that suggests that in a two-way race Trump would run even with or slightly ahead of Cruz and Rubio:

If there were a two-way race, it is certainly possible that the other candidate could end up winning, but it would probably be a very close-run thing. At the moment, Trump would appear to have the edge over Rubio, and is essentially tied with Cruz. If a two-way race happened right now, it’s not at all obvious that Trump would be the loser in many of the early states. It’s true that Trump seems to benefit from a large, divided field in the early states, but we shouldn’t assume that he would lose in a two- or three-way race. Trump becomes more likely to lose once he has fewer opponents, but if his remaining opponents are Rubio and Cruz it’s not that difficult to imagine how he could fend off both of them.