This is like when Andrew Breitbart died. There just isn’t a replacement.
The Beatles clearly were the first mega group, had a deep influence (Ozzy got into music because of the Beatles) and sold more albums in the US (183MM units as of today) than any other band. Their 12 album releases from 1962-1970 remain staples.
Hendrix released four albums from 1966 until he died in 1970. Those albums have sold maybe 10MM copies, and Hendrix's total catalog has maybe sold 20MM copies. But the man has influenced the guitar players of the planet more than anyone else. His much narrower musical influence is arguably still white-hot.
Rush is the Beatles. Andrew is Hendrix.
And perhaps most importantly, we all thought Music and the guitar was OVER when the Beatles broke up and Jimi died...then we got The Who, Zeppelin, the Police, Rush (the band), and Eddie Van Halen, Steve Howe, and Steve Vai.
Of course, if people want to mourn, let them. Rush did a LOT of good. But we all thought we'd never see a great one like Reagan right before some guy took an escalator ride in 2015...