We're stuck between a rock and a hard place.
If black people en masse decide to stop voting Democrat (and either stay home or vote 3rd party) then that's essentially handing the country over to the GOP which will make the situation even worse. If we continue to vote Democrat then votes will be taken for granted. Plus there's the fact that white voters tend to be averse to any policy they view as specifically enacted to help minorities (reverse racism blah blah blah), and the Dems are worried about not getting a high enough share of white voters.
So there's no good option. At all. But I'll generally vote Democrat in national elections because it's the less bad option and I tend to agree with them more on non-racial issues (climate change, drug policy, etc.) than I do with Republicans.