Glow and Warehouse pretty much died...
I don't think Glow is dead. I was visiting Glow in the past alone and as you said it's hard to kill NPCs. Glow requires at least 2 players to successfully loot it. You can't just enter to Glow and play as monkey or rush. It's doable, mate.
Warehouse?
I don't do it very often so I can't say if you're right or not. It's too hard for me and my friend to kill slags.
75% chance that the whole community will work together to destroy those First-Aid Spam NPCs, before focusing on killing each other
I can agree with you that many "FA Spam NPCs" and "High HP NPCs" should be reworked. The first solution is that removing FA skill for "High HP NPCs" because it's very annoying when you can't kill it.
New Reno? Yeah, Its more than a 'normal' city like Redding etc. by know, Commercial Row shouldn't be spawning T4, since- yes, its soloable, too easy to farm, three slags that can be lured one by one- it should be spawning a 'normal' magic locker, T3 items- no T4s... The Sewers? Waste of Bullets, ask the players, it's not really worth our time by now.
Reno is good place for small PvP and I can agree with you that "magic locker" is needed. Something similar to Warehouse with few slags, loot should be T3 with bonuses and maybe drugs since it's place controlled by drug dealers and gangs.