These singing competition shows are having switcheroos all over the place! We saw Britney Spears and potentially Khloe Kardashian joining X-Factor, Mariah Carey, Nicki Minaj and Keith Urban joining American Idol (in place of J. Lo and Steven Tyler) and now, Christina Aguilera and Cee-Lo are out for season 4 of The Voice, being replaced by two equally…if not more…famous voices. No worries, though, Xtina and Cee-Lo fans: they’ll be back for season 5! Who, what and why? Details below. Marisa Mendez