3 out of 5 classic EQ hardcore PvPers agree: we won't see a system like classic EQ again.
I think the unlimited level range thing works with factions, but I also think 2 faction systems are DEAD. One side will always be larger, and some much more so/out of proportion (hi2u evil race team on pvp server, duh) but at least the 2nd, 3rd and even 4th factions run into each other at times and have some good fights on a multi-team server.
The open world system is good for this, as long as there aren't "objectives" aka zerg points... or you go with the system Warhammer finally implemented with supply lines. Also, if there are multi-faction servers (and there, so help me god better not all 2 faction Horde/Alliance style servers), they need to be sure to show on server select which team has X number of active players (update it per week imo). This high/low doesn't help as the game goes on because the more relevant issue becomes "who has the most high level players at prime time". But, like I continue to preach, make it FFA and open world without zergable Wintergrasp-like content. Having a strong number of players should be a good thing, but not at the expense of losing targets. Further, PvP really shouldn't even be mandatory or have its own gear set. However, you should be able to take a piece of gear from people.
To this day I can't understand making a grindable system like battlegrounds when the most fun is definitely random world pvp encounters.