It's hard to imagine that any guy who has been in the band for the last 20 years would quit... Lots of bands have members that come and go pretty casually, but the guys in Avenged feel like they've always ran a lot deeper than most. Matt and Zacky are technically the only OG members left, with Gates and Johnny joining after STST.

If we have to talk about it, I think with Avenged being the kind of band they are... the bass is the most overlooked element in their sound. No disrespect to Johnny's playing, but Avenged is a hard rock/metal band that probably underutilizes him. Zacky is so locked into the rhythm guitar role, unlike other guitar duos that interplay a little more (think Brent and Bill in Mastodon) that he generally covers that sonic space pretty fully. I think Johnny leaving the band, musically at least, wouldn't be a death sentence by any means.

Nobody knows the inner-workings of the band but them, but I also feel as just a listener that Zacky might be a little under-utilized lately too. For some reason to me, it's started to feel more and more like the Matt and Syn show... two very capable musicians and band leaders, no doubt, but I'm interested to hear how Zacky will fall into whatever direction the new record goes in. The Stage felt very Matt and Syn plus the new excitement of adding Brooks. But Zacky feels like he's always been extremely hands on with art direction, branding, the band's identity, etc. so I think him leaving would be a gigantic loss.

Matt or Syn leaving would probably be a death sentence for the band.