Madonna may not be in the Billboard Top 10 any longer, but to those acts who are, she’s the mother hen.
If you still think Madonna is irrelevant, cast an eye toward some of her one-time contemporaries who have been farmed out to Las Vegas.
Britney Spears was once touted as the new Madonna — but she now churns out her old hits at Planet Hollywood.
Mariah Carey’s last album “Me. I Am Mariah…The Elusive Chanteuse” was a spectacular flop, and she, too, is likely to become a regular fixture in casino land.
If rumors are to be believed, J.Lo will be next on the desert-bound gravy train.
Meanwhile, this fall, Madonna will be playing to sold-out arenas all over North America and Europe on her “Rebel Heart” tour.
Not only does pop music still want Madonna, it positively needs her.
http://nypost.com/2015/03/07/why-madonna-still-matters/
All three are completely different so I don't understand the comparisons, especially when Britney and Mariah both seem to like the idea of performing in one place rather than touring. 
