For instance, I want to hear Billy Joel's "She's always a woman" covered by Australian band Crowded House. This cover does not actually exist, but if AI style transfer could do for music what it does for art, or for voice / face mimicry, then this cover could exist, albeit a synthetic cover rather than an original.

When will this sort of music style transfer be possible by AI, in the same manner that artistic style transfer allows one artist's "style" to "cover" the work of another artist?