I tend to think you're right. If FM were still under contract with Warner Bros, I can imagine Warner Bros would highly encourage Stevie to jettison recording a solo album in favor of a Mac one. This is because the Mac tends to sell at least 50% better than Stevie does solo. Plus, Warner Bros has a much larger Mac back catalogue they can capitalize on vs Stevie's solo career. When established artists like Fleetwood Mac release new albums, their old albums tend to see a spike in sales at the same time. Especially with Christine back in the fold, Warner Bros would highly encourage a new Mac album vs a Stevie solo one. My guess is the band probably hasn't chosen a record label yet. But I could be wrong... maybe Warner Bros wants both albums out quickly to offset costs & for them to bolster each other's success.