The following scenario assumes Trump runs a campaign virtually identical to his real one.
Trump - 334 EVRepublican - 204 EVGive or take FL, NM, NV, MO, KY, IN, and WV.
While Trump running a campaign on his stances would be suicide in a Democratic primary, if he was the Dems' nominee 2016 would probably be a realigning election to some extent. The Republican would do better in places like the Sun Belt and win over VA, NM, CO, and NV and traditionally Democratic states (but not to the extent that it flips, unless there was a third party). Trump would outperform Clinton in the Rust Belt (duh). The Republican might win the PV, though it is most likely Trump would crush the EV.
This is the best Trump could do:
399 -
139A close shave for Trump:
271 -
267A lot of states are probably tipping points, though NH is probably the closest one.
The best the Republican could do:
332 -
206