Currently, phoenix provides zone controling and scavenging. I think there is should be much more features. Most of people sit in HQ carebearing and do absolutely safe quests without any pvp, its horrible for game making its less pvp. So my ideas to improve phoenix:
Merchants in the core selling t2-t3 items with lower prices than in HQ. Appear and dissapear randomly, better merchants appear closer to center of the city (hospital). Also, they should be very good guarded, making killing them extreme risky.
Quests in the phoenix - obtain unique item, kill npc/patrol, kill some players of enemy faction, etc...
Items/npc will spawn when you enter quest location (district of the phoenix)