The most important wildcard is whether the moderate wing of the party would prefer Trump to Cruz if Ted emerges as a finalist. One of the great tensions in the Republican coalition is the distaste of the moderates for the social conservatives, who actually mean what they say about traditional values, abortion and religious liberty. The RINO's want the social conservatives to work their tails off, donate, and vote ... and then go away, to be seen but not heard. Cruz is an unabashed evangelical and is likely to embarrass the country club Republicans by actually nominating judges who will reverse Roe, defending Christian business people who don't want to participate in gay marriages, and supporting school choice. The truth is, a lot of the establishment Republicans have made their peace with the left on sex, gender, and race issues, and they wish the traditional values crowd would just go away. These people, of course, regard Cruz as an extremist.
He won more of the Republican vote than the 1st, 2nd and possibly even third placers combined (maybe off by a point or two). Whether you want to call it a plurality or a majority or whatever, Trump clearly dominated it to the same degree as he did independents. 70 percent of the total vote, by the way, also claimed to be conservative, with 25 percent of them calling themselves "very conservative." Trump dominated them too. 30 or so percent reported as Moderators, and, of course, Trump dominated them as well. His only real threat was with the moderates, where Kasich had 28 percent and Trump only 32 percent of them. New Hampshire only had 30 percent of its Republican voters identify as moderate. You will not be having this many self-report as such in South Carolina.
If the GOPe candidates all coalesce into one candidate, Trump might have some trouble in more liberal states, but then Trump so dominates the conservative vote-- and the conservative vote so dominates the primary process to begin with-- that it probably won't be a problem, and Trump's numbers will probably even grow even bigger among conservatives once they realize that they must unify behind the strongest conservative in the race as these other people drop out.
And again, with a Republican primary built for more moderate candidates, Trump dominated to such a degree that even if multiple GOPe candidates left and ALL their votes went to Bush or Rubio, Trump would either be tied or still ahead at current numbers.