Adele is the biggest artist out right now in terms of sales but this is not really the show for her. Yes, she's the sort of artist who follows in the footsteps of Whitney and Mariah (pure vocalists who command the stage by virtue of their voice). However, the difference between her and the aforementioned ladies is that they had/have upbeat dance-able numbers as hits in their discography (especially Whitney). I would love if Usher would be given the chance to headline (with his mic OFF, no shade, lol). He has hits upon hits to keep the crowd entertained and he's still a talented performer regardless of age. J.Lo could slay too and so could Gaga. Or perhaps they could get a legacy act to perform like Tina Turner as suggested above.