It seems as though music is moving away from traditional types, but these traditional forms are not in danger of dying out. That being said, they still just serve a niche market that does not have widespread appeal. Given this, they probably won't become fully mainstream, and they will relish in this fact.
Highly traditional forms of music such as flamenco will never become fully mainstream. There is too small a market for this highly specialized music and not enough people will demand to hear the music on the radio or download it. There will always be a strong demand from a small group of fans.
Highly traditional music will never become fully mainstream. Flamenco is very rousing music, but is not very well known or accepted outside of it's culture. Every ethnicity/culture has it's traditional style of music, but it seldom appeals to the masses. The only exception I can think of is Reggae, which Bob Marley brought to the entire world.
This music requires a certain culture and a certain type of people to engage in and actually enjoy it, dance to it, and use it to its full potential. Flamenco is a beautiful dance and musical genre, but I cannot think that it will ever reach the heights of rap.
I don't think traditional forms of music will ever become fully mainstream. Flamenco (for example) has not exactly been hidden away until now and just been discovered. It has been there in the background for many years for people to see and listen to. If these forms of music were ever going to become mainstream, it would have already happened.