Black Americans make up the 9th largest economy in the world. That's larger than some western european countries.
No Limit, Cash Money, Rap A Lot all made money in the hood well before they got to MTV. It is very arrogant to think that black dollars couldn't solely support black music.
If we take it to a different arena, black gospel is black owned on every level. Labels, presses, studios, distribution, concert halls, ... on down the line. Maybe you got a bebe and cece winans on a big lable, but the vast majority is within the black community.
Hip Hop has never needed whites for anything. The fact that white folks enjoy and benefit from hip hop is really a side event to what is really going on within the culture of black america. Don't even get me started on Tejano or Salsa and Merengue. Our Latino brethren have shown black folks that you do not need white money at all to flourish.
Not that I think white folks involved/controlling hip hop is necessarily a bad thing, but they aren't needed.