To be totally honest people that have acknowledged great singing capabilities, usually don't have that talent forever.
The aging process in all of us has diminishing effects regarding abilities in vocalization singing.
Problems accumulate though with professional singers for this has become their career and their popularity is incumbent surrounding that very capability.
Pretty hard for a person whose accumulated so much popularity and fame for having that noted capability and to come to terms with themselves
that capability is no longer there and can never return to them.