I don't think she can keep her voice healthy enough to record one solo song let alone an album without sounding hoarse. And don't' get me started about an entire tour.
The only two who actually have a voice for solo work is Dinah and Ally but they aren't marketable without a complete overhaul. Lauren's voice fails if there's a breeze in the wind, Normani can't stay on key to save her life and Camilla's voice is annoying as hell if not in small doses as proved in cinderella.