That is sad to hear and another loss of a top quality musician. Even though I was always more of a hard rock/metal guy, I always had great respect for the musicianship in Toto.
Before becoming "Toto" they were all highly regarded studio musicians that played on numerous major albums for big name artists, and Steve Lukather is actually an amazing session guitar player who supposedly played on almost 1700 albums!
A couple of my cover bands back in the day did our own "rocked up" versions of "Hold The Line" and "I'll Supply The Love", and I always thought "Rosanna" was a musical work of art, composition, arrangement, performance and production-wise.
I agree with James, 59 is way too young to go.
Bob