To me it seemed like there have been two "phases" within the past 10 years of the decline of her voice:
Phase 1 - the shouting, as we saw strongly in the 2009 Fleetwood Mac tour. Sustaining notes was replaced with shouting
Phase 2 - although the shouting may have gotten better in recent years, now shes struggling to hit the notes in the already lowered-key arangements that she previously didnt have issues with.
She can abruptly reach up to those higher notes like she does on the "I'm getting older too" part of landslide, but those gradual climbs from a high note to a low note or vis versa are where her issues really reveal themselves.
__________________
|