Immortality exists in several forms, each with its own imperfections.
A lot depends on how you view what comprises a “self”.
Can a pianist be so well practiced and studied in Bach that the intuition is fine tuned as such that a brain scan of Bach and a brain scan of the modern pianist would show similar structures with regards to musical areas?
I think so.
Does that mean Bach is back in that pianist?
It’s all how you view it.