http://www.stltoday.com/news/local/govt-and-politics/democrats-say-they-ll-target-republican-ann-wagner-s-congressional/article_0b86a4d2-f069-5e25-a393-bf2ffde452b6.htmlMissouri-02
It has rich suburbanites who are still turned off by Trump and some old school redneck Democrats who voted Republican in recent years but maybe more open to voting Democrat now. It did make a swing to Clinton and is not that Republican locally at all.
Wagner's large margin's of victories should not scare anyone. No Democrat has seriously contested the district this decade. Still if a Democrat wins this it is likely for only one or two terms. Population shifts and redistricting will likely make the district solid GOP after 2020 elections. The only chance for Democrats to have three of the eight congressional seats in Missouri after that will be hoping the GOP splits up MO-05 and creates a dummymander.
Still it would be much much easier as an open seat and we must remember it still voted for Trump 51 to 42. On the flip side Kander v Blunt was essentially tied and Democrats are not exactly absent in local politics here.
Also remember this:
tl;dr Not impossible district and viable for Democrats to compete it but it will not be as easy as other targets for sure.