Simple.
Over exposure on anything kills its exclusiveness - thats the main reason people stop wearing a designer brand.
Happened with Tommy Hilfiger, Ed Hardy.. and I can see True Religion going under next.
Once the exclusiveness goes, and people stop wearing, one of two things happen...
The price stays the same and even less people bother as its not exclusive but expensive.
The price goes down to the point where its not designer anymore.
With FUBU you have the situation above, plus the fact that people dont rock baggy clothes so much.
The brand as a whole is worthless unless they start from scratch.