I imagine LOG and Trivium will pull different groups of fans than just Megadeth and a few other thrash bands.   Pre-pandemic, hell, even pre-married life when I frequented more live metal shows I noticed their was a distinct death metal crowd in Vegas that did not usually go to thrash metal shows.   
About a decade ago I went to the Summer Slaughter tour and it was two distinct crowds.  The younger guys were there for bands like the Faceless, Job for a Cowboy, and Between the Buried and Me.  The older crowd took over the pit during performances by Goatwhore, Exhumed, and Cannibal Corpse.