Not upset at all. The thing about the artists I love is their dexterity in other fields and/or their contributions outside of music being overwhelming. Janet, Brandy, CK, and Utada have all been around for a while, so I don't mind if they permanently retired from music. The first three are really good actors, and Utada is an amazing composer, so I'm fine if they retired.
Ciara, on the other hand, has so much potential that isn't utilized ever so often, and I'll be somewhat upset if she retired, because I'm sure she has great material ready.
