Won't take anywhere near that percentage. If only 10% of black voters went from 'Rat to GOP, putting the black GOP vote around 20% - and the fraud machine was stymied somewhat - the 'Rats would lose so many statewide races that their chances of electing presidents and controlling either house of Congress would be slim to none. (Getting tough on illegal immigration would be an issue that would resonate in the black community, but it probably won't happen with the current RINO bunch in Washington.)
The midterm sweep left 1-2 slivers of coastal territory and splotches of interior to Dems. Heck, Dems have literally "hundreds of votes" under their control (/snix).
Democrats now control votes in the inner city, gangland strongholds, sleazy Hollywood motels, landfills, Indian reservations, pineapple plantations, fast food joints, Boston beaneries, coastal clam shacks, surf shops, flop houses, gay baths, and payday loan mills.
What the Republican takeover looks like as of midnight 11/5---Alaska and LA went Republican later.
Midterm Map courtesy of http://www.nationaljournal.com/politics/here-s-what-a-republican-takeover-looks-likes-20141105