While I'm not in favor of multiple amulets, it might not be a bad time to suggest a mastery amulet "reboot". They came out around Celestia before amulets routinely added multiple things. I'd kind of like to see new updated mastery amulets (even if they are tied only to higher levels) to go with new dual mastery gear. Having recently re-played several characters at lower levels, I find I kind of miss the fun of effectively dealing damage from a second school and this might be a way to kind of "reboot" that at higher levels.
They can do it in a way that allows you to get an extra amulet spot BUT take away something else. For example, a ring or athame called "extra amulet ring/athame" that will grant you an extra amulet spot whne equipped. But the thing is, the ring/athame won't do anything else so in exchange to get an extra spot for an amulet, players lose the spot for the ring. This can create new strategies in combat.There can even be other way around like amulets that grant you a ring spot or somethings like that.