Is Say You Will a fitting end to their legacy?

[secret love]

Pretty much I started this to discuss the following questions

Is Say You Will a fitting end to Fleetwood Mac's legacy?
If not, is Buck Mac duet album a fitting end to their legacy?
If Stevie decides not to be involved in making a new studio album, will it fracture or split the band completely?
Is a tour possible or worthwhile behind the Buck Mac duet FM album with Stevie involved but not singing her own new songs? (She would still be doing tambourine and backing vocals on the live versions of Chris and Linds' songs)