You're right...as more Blacks have abortions......in all probability one reason for Obama's 'open border' for illegal children and their chaperons. 
Because identity politics work for the Dems and will increasingly be more effective as the demographics of this country rapidly change. By 2019 half of the children 18 and under will be minorities as defined by the USG. By 2043 half of the country will be minorities.
Government policies reinforce group identity. Certain groups receive advantages like minority business set asides, affirmative action, quotas, etc. The Dems will use identity politics more and more as they become the permanent majority party. Demography is destiny.
You're right...as more Blacks have abortions......in all probability one reason for Obama's 'open border' for illegal children and their chaperons.