I mean we're not far off with Vocaloid. Ever seen a Hatsune Miku concert [0]? All that needs to be met is "generate lyrics and song by A.I" and I've already heard a number of A.I generated that could work well enough as backgrounds for a vocal-heavy track [1]. The hardest part would be training a neural network to generate Miku's vocals and maybe creating the lyrics for the song.

[0] https://www.youtube.com/watch?v=dhYaX01NOfA

[1] Just one example: https://www.youtube.com/watch?v=LSHZ_b05W7o