not true.
Latinos are moving into inside the beltway PG (Oxon Hill, Landover, Temple Hills, etc.) as Hyattsville/College Park/Mt. Rainier area gentrifies and diversifies. upper middle class blacks are outside the beltway like Bowie, Ft. Washington, Brandydwin or moving out to Charles County or other places in Maryland. like Montgomery County, Howard and Anne Arundel. PG has a large Caribbean (mostly Jamaican ) and very large African population (especially Nigerians and other West Africans), mostly in the northern and central parts of PG.
DC 's black pop. is like 95% AA and PG's blacks is more like 75-80% AA. only places like Boston, NJ, and Miami have super diverse black pos.