There are no Congressional Districts in Missouri capable of being flipped. They've been gerrymandered to hell.
But there are some in Texas, for example, where if Hispanics registered and voted then many would be surprised by the results.
Frankly, I don't see why some Democrats whine about something like that.
Besides 23, what could possibly be flipped in Texas?
Districts that might flip in a 1964-style wave include: TX-6 (R+11), TX-7 (R+13), TX-14 (R+12), TX-17 (R+13), TX-21 (R+12), TX-24 (R+13), TX-25 (R+12), TX-27 (R+13), TX-31 (R+12) and TX-32 (R+10). But 2016 is not going to be like 1964.