She doesn't actually need it in what is appearing to be the likely scenario. Getting the 98% like Obama did in 2008 would actually make the overall non-white vote closer to 90-91% Democratic (rather than the 89% figure in 2008); because there are slightly more non-white voters than in 2008 and because Latinos/Asians are swinging Democratic. Blacks being 95% Democratic would probably be enough to balance it all out.
However, because Johnson pulling an extra couple of points is now also a reality, that number could be lowered even more. If Johnson gets 2.5%, then Hillary would be in a statistical tie with Trump if she merely got 23% of the white vote, 92% of the black vote and 65% of the rest (85% of the non-white vote).