Have you been a member of a Xenforo forum that closed? Why did it close and have you ever tried to save a forum from closing or took in their members to your own forum? Most of the Xenforo forums I was on that closed were admin-type forums such as XenFans, XFShowcase, XenAdmins and XFDriveby. I have closed two of my own forums, BlackGamer and Xen-SEO. I have members on my site 8th.us from two xenforo forums that closed, LurkingGlass and Desitamashah. In all these cases, the webmaster closed it themselves. It seems to me that forums only lasts as long as the webmaster gives a ship. I guess thats the main difference between forums and sites like Facebook and Twitter because if the owners give up, they won't close it, someone else takes over.