I think this topic is by now beating a dead horse, but [url=https://www.roleplayerguild.com/topics/168339-expanding-horizons-the-revival/ooc]this thread[/url] and [url=https://www.roleplayerguild.com/topics/169759-persistent-world/ooc]this one[/url] may be of use. Hell, there's probably a few other ones out there discussing EH that I missed since everyone was discussing it.

Anyway, I do think that EH failed for several reasons. The majority of the mod team overseeing it seemed to have literally vanished off the face of the Earth, and you had to jump through so many damned hoops just to apply for a CS from gauging the majority of your sheet by numbers/power level to having multiple people approve your CS even though there was hardly anyone to even approve of them. 

Additionally, EH tried to be too much at once with smashing every possible setting/genre together to give people freedom to RP what they wanted within the setting, which is nice on paper, but ultimately leaves--in my honest opinion--no true focus to the setting, especially a setting without any overall plot outside the threads themselves until they, inevitably, had died too. 

What I'm trying to say is that EH was hardly an example of a PW. For instance, the United Federation of Planets, a group ran by the staff of EH, was supposed to be the largest superpower in the galaxy, but it didn't have much impact on the setting despite being so powerful. With everyone off doing their own thing in what lore was available, nothing really changed in the setting. Castles didn't change hands in a war on Ecetopia, manhunts to end the reign of a bloodthirsty gang hooked on some drug on Frixion Prime never happened, etc. 

Things didn't really change within the setting; it more or less stayed the same even after everyone grew bored of EH. A PW is nothing if events don't actually affect the setting outside individual roleplays.