Check state polls for Hessen here. From the last poll, if the Left Party would trip over the limit, it would actually prevent a right-wing majority (though probably still only a Grand Coalition under Koch would be the result). However, you are right it is far away, and who knows what populist theme Koch plans to ride until then...

While working-class Frankfurt and the Protestant Northeast may be SPD strongholds, the belt of Frankfurt (where I lived) was mixed, the sides of the Taunus are full of well-off conservatives, and the East (region of Fulda) is dominated by an arch-conservative CDU. (Do you remember the Hohmann affair? "Tätervolk"? He was from there. [Incidentally, one eighth of my ancestry also came from there.])

_{*Lunatic*, n.
One whose delusions are out of fashion.}