Well, it happened everywhere in 2006 and 2010, sooo...
It even happened last year with Kander. Plus, she is an excellent fit for her state, extremely popular and was underestimated in 2006 and 2012 as well. So yeah, I think she is very safe in 2018, even if it turns out to be a GOP wave year. Keep in mind that she beat Talent and Akin and the GOP bench in MO sucks.
Anyway, even with polarization, it really depends on whether 2018 is a neutral/slight GOP year or a good Democratic year. Especially in a state like Maine or Michigan, that matters. So it's not easy to rate those states at this point.
