She has performed her other jobs well, so why would anyone think she would be an awful President? Definitely a second term.
It's not a question of how good she is, unless things stop polarizing over 4 years and reverse, half the country is going to hate her on principle and there'll be suspicious liberals anyway.
Given how unpopular both sides are right now, 2020 is probably going to be a rout to fix the errors of this cycle.
If trump wins, he'll end up like Jimmy Carter (as if his campaign didn't already have a lot of resemblances), with Paul Ryan and the remaining Tea Partiers being like the 1974 Liberals batting heads.
If Hillary wins, she'll probably end up like H.W.