I was having this discussion with my 15 year old daughter and we were trying to figure out which bands of the past decade would be hall-of-fame caliber. The BEP/Fergie have a very interesting intermixed style which is awesome on a few of their songs. I can appreciate the hits, which are great, but can't listen to the majority of an album like I can with many other bands that don't seem to have the hit power of the BEP.
As far as the 10 and 11 year old following, I wonder if the parents are really listening to the lyrics of these songs which are filled with foul language and very mature subject matter.
My guess is that they will not have the staying power and don't represent the future of modern music.
Finally, anybody that doesn't think Fergie is H-O-T should seek a professional consultation.