Missouri Republicans are in deep trouble over this, and will continue to be until Hanaway drops out of the race and Hancock resigns. Hanaway is definitely now facing a steep, uphill battle in the primary, and it looks like it's going to be as bloody as the 2012 Senate Primary. We'll see who Rex Sinquefield decides to throw his money behind, but he has already wasted about a million bucks on Hanaway. Koster is definitely the favorite to win now against whoever Republicans put up, who is likely going to have about 0 name recognition. I think there is a possibility that Tom Schweich's suicide(especially Danforth's condemnation of the state GOP) is going to hurt Republicans generally in Missouri next election.
I think that it will hurt Republicans to a point as well on the state level, though I still think that whoever the Republicans nominate will still carry Missouri (though by a closer margin that in 2012) and I think that Roy Blunt is still favored for re-election at this point, as the Democrats don't really have that strong of a bench of possible Senate candidates.