Anytime you take two huge and popular stars, such as these to extremely famous singers, it will be a very entertaining and popular show. I think these to should pair up and sing a song on stage, since they are both great singers and can combine to provide a great show.
No, Madonna and Miley Cyrus should not sing anywhere. Madonna
has had her many years of fame and adulation, and Miley needs to spend a few
years taking classes and growing up if she wants to last. The idea of these two
over-processed, miked up, pitchy, lip-synching superstars sharing a stage
is actually frightening.
I think Madonna and Miley Cyrus would enjoy performing a duet together on stage. I for one would enjoy seeing it. I believe that Madonna is an older, more experienced version of Miley and the two of them would be capable of some real fireworks together on a stage. I also think that Miley could profit from Madonna's experience as an entertainer.
Madonna had her day. It can even be argued that she had a couple of decades. That is fine. Miley has, for all media purposes, become a pop sensation in her own right today. Whether someone is a fan or not, sales do not lie. This is fine. So why not let them perform together? They are, after all, free to perform what they want, when they want, and how they want (just not always to anyone they want.)
Given Miley Cyrus completely switched up here look, an attribute originally created by Madonna, I feel it would be more than suitable for them to sing a duet on stage together. I hold Madonna to a higher standard then Miley Cyrus however. It seems Madonna has done some controversial things in the past, but never to the degree Miley Cyrus has done.