Anything you can do in those games they can slipseat into H1Z1
Flying vehicles (planetside 2), skills/ability systems (EQ:Next), crafting (EQ:Next + Landmark), gun mechanics (PS2), making forts (EQ:Landmark), intuitive clan management (PS2, EQ:Next): they don't have to reinvent the wheel. Almost everything they could want to put into the game already exists. It's just a matter of tweaking it, modding it for it to fit with the game. And discovering what it is they want to put in, which they're heavily invested in the survivor game niche/community to get ideas.
For instance in an interview w/ Lirik, Whisenhunt explains how he wants shooting to behave on release, will be a lot closer to CS:GO than Planetside 2; a lot of recoil that has a pattern you can match when mastered, with low recovery time (tapping/bursting won't move a xhair if you're not moving your mouse).
It's going to be crazy to see what a final product from an AAA company making a free full loot survival game might look like. Especially since their item mall will consist of cosmetic and at best PvE boosters (timed buffs to reduce damage wolves do, etc). One of the more relieving thoughts about "yet another survival game" is that it's not going to be community servers. It's an MMO so SOE will be providing the servers. And their goal is 1,000 players per server at release (in which the map will be much bigger than it is now), and grow the player capacities as they add to the map-size, like they did with PS2. The big red flag; POTENTIAL!
