Christie, Paul LePage (?), Ben Carson, even Sarah Palin. But nobody will do very well, for a variety of reasons.
1) Trump loses. See also 1964, 1968, 1976, 1992. When one ideology tries and fails, another will succeed. Someone either more conservative, like Cruz, or moderate, like Sandoval, will lead the polls.
2) No Trumpian candidates are very good. Self-explanatory, but of the names I listed above, all are bad politicians who won't succeed.
3) No more Obama. With Clinton as president, the landscape will be completely different; The opinions of the electorate will have shifted. In addition, race relations will not be in the forefront of everyone's minds with a white president.
4) Trump was one of a kind. Trump's campaign was all about tapping into the right energy at the right time with the right conditions. None of these candidates have the bragging, experience, or lack of self-restraint that endeared Trump to the base. In addition, the conditions of the race will be different, making it harder for anyone like Trump to win.
5) Stronger field. In 2020, people like Ryan, Gardner, Haley, and Ernst, who are better candidates than their 2016 counterparts, will likely run. The field as a whole will be much, much stronger.
Hope this answers your question
