So if I were waving my hand, I would divide the game into 5 types of zones (ignoring blue, red, and gold).
Starting zone. Your level is your level. Has no ambushes, holiday events, etc. It is always the same in effect (although it can change looks for the seasons). A safe haven for new players.
Standard zone. Your level is your level. Has ambushes, holiday events, etc. Has radio missions and older generic mission arcs. A core set of zones that is intended for general play. Steel Canyon, Talos Island, PI, etc.
Story zone. Your level is exemplared to the zone level. Has no ambushes, raids, holiday events, etc. It is always the same in effect and may always look the same - Croatoa, Cimmerora, etc but also Faultline, Striga, etc. Arcs are designed for stories and soloing not necessarily for teaming.
Hazard Zone. Your level is exemplared to the zone level. Has no ambushes, raids, holiday events, etc. It is always the same in effect and may always look the same - Hollows, RWZ, etc. Arcs are designed for teaming not necessarily for soloing.
PvP Zone. As they are now.