[Greetings_Puny_Humans]

Two-thirds continue to vote for someone else.

I just did the math:

If we just take Republican voters (your best scenario, with the independents all gone), and if Kasich goes, Bush goes, Fiorina goes, Christi goes (and he's going), and all their votes go straight to Rubio:

That total number is 37 percent to Trump's 35, only over Trump by 2 points.

Considering how unlikely such a scenario is to begin with (Christi actually does appeal to conservatives, and won 4 percent of "very conservative" and 9 percent of "somewhat conservative", and if almost the entire field drops out, we have to assume that Trump's numbers do not increase in any way), Trump is doing very well indeed.

[sphinx]

So by your math, you have Trump second in a three man race. LOSER. But what you sketch is a plausible scenario, with Rubio, Trump, and Cruz as the finalists. Do the Cruz supporters bolt for Trump? Unlikely; Trump is poison on the social issues and big-government activist on economics, while the Cruz base is heavily tea party and evangelical. It would be easier for the conservatives in Trump's camp to move to Cruz, unless they are actively anti-the traditional values crowd. Right now this is masked by the Trump bandwagon effect, but if the perception of inevitability is punctured, all bets are off. A lot of Trump's supporters just want to be with a winner.

If Rubio falters, the question becomes whether his supporters would break for Trump or Cruz. The tension between the traditional values voters and the culturally liberal RINO's may be the decisive factor.