All the reward spots will most likely not be claimed but seeing as this is the limit Obsidian chose they have to consider this as a possibility.
That means 6 enemy parties, 50 items, 3 inns/taverns and 200 NPCs will be designed by contributors. In any RPG i've played this would be a huge chunk of the sum total.
I mean, I can see the want to reward high tier backers but i think most people wanted OBSIDIAN to develop this game and not random people/communities off the internet - who will mostly likely have no experience in game design and have no firm grasp of the feel and lore of the game. Ma