When I posed the question of what factors lead to "world music" artists crossing over into a more "mainstream artist, I got this compelling entry from journalist/author Elijah Wald...
As far as I can see, the three main factors in crossing over are what you are calling "celebrity endorsements," similarity to already familiar styles, and it also helps to have a built in home-folks fan base.
That is, the groups that have crossed over need first to be heard by large portions of a "mainstream audience," and second to appeal to that audience's existing taste. The biggest crossovers, things like Buena Vista and Ladysmith, had celebrities to bring them into the public eye, but then flourished because they resembled things people already liked--old Latin dance music and choral/gospel music. Buena Vista sold way bigger than Ladysmith because it both had a substantial Latino audience and --more importantly-- rumba/mambo has all the appeal of Frank Sinatra without any of the cultural baggage.
Some semi-crossovers have managed the illusion of being much more successful than they really were because they had enough of a core immigrant audience to create the illusion of broader popularity--Nusrat would be a perfect example of this, filling huge halls largely on the basis of immigrant fans, but fooling people who weren't doing the demographics into confounding the numbers of his relatively few, but very vocal mainstream fans with the numbers of tickets sold. But it is not all smoke and mirrors--that immigrant fan base gave Nusrat the opportunity to reach a much broader audience than he could possibly have reached without the packed, exciting concert tours, and the same goes for Cesaria Evora and Mariza.
The artists who feel trapped in the "world music ghetto" are making the assumption that they would fare better in the mainstream. Most of them are wrong. Like the "classical ghetto," the "world music ghetto" provides grant- and arts council-funded bookings. Anyone whose biggest gigs of the year are non-profit-funded concerts in parks, at city festivals, and at venues like Grand Performances or for concert promoters like Boston's World Music should thank their lucky stars they are not considered "mainstream." A lot of people who will fill a 1,000 seat room to see "world" acts at $20 a seat would not show up if the same concert was in the same room at a ticket price that actually paid for the show.
-- Elijah Wald, author and journalist, www.elijahwald.com
