Lots of long-time regulars leave all the time, to be honest. I can't recall anybody leaving who was a major contributor to War Room threads in the past year or two, apart from the troll accounts. It's pretty much always been the people trying to stir things up that have been the most active contributors.
If anything will cause this sub-forum to wither, it will probably be the policy of not allowing new accounts to contribute. Prevents people from coming in here with their alts and troll accounts, or just new posters giving their 2 cents on thing (until finding out that they probably shouldn't), which is traditionally what has kept this place alive.