This is just a guess, but I somehow doubt that NWN2 will have the longevity of NWN1. I think NWN1 greatly profited from the numerous modules and persistant worlds, and right now it pretty much looks like Obsidian missed the train on this one with NWN2. The toolset, while not as complicated as often described, is still very complex and creating areas is much more time consuming than building areas in the Aurora toolset. I hope I'm wrong and we'll see a lot more of NWN2, but I have a bad feeling there...
Yep. Forced registration with Atari (as opposed to just creating a Bioware account), forced PWC file requirements, lack of a standalone server and memory requirements have all contributed lack of interst in Multiplayer. Sadly, Rob McGinnis at least one time blamed the word of mouth of players for sticking with NWN1 for MP.
Ironically, Obsidian allowed URL links on Gamespy for third party content like haks which Bioware still doesn't have after repeated complaints. Unfortunately, they were launched broken.
If there were any justice the PWC
Custom content has been hurt by unwillingness to give out tools until very recently.
Promises of a new, improved DM client have never materialized. Problems here were twofold: Obsidian didn't like it as it was and thought it needed an overhaul but for times sake they didn't; and they nearly took it out altogether. Focus groups from Bioware proved very unhelpful in this regard because both companies simply took note that it was the least used feature.
The big mistake in this regard was responding to the complaints of the first OC and focus groups. They came out of the gate well but have fallen back as the race got longer.
Obsidian didn't have the vision that Bioware had when they initially planned NWN and it took a long time before it was understood by fans. Bioware has dropped that vision it too thanks to the aforementioned focus groups.
I wouldn't be surprised to see the Mysteries of Westgate Adventure Pack to be the last thing to come out of NWN2. Atari no longer has money and Obsidian probably feels they need to move on their new projects.
I'm hoping for MP, a Standalone Server, and a Toolset with Dragon Age. If Witcher's Djinni Toolset ever supports MP there's some hope for that too.