Your list omits the valid reason why it stopped: https://news.ycombinator.com/item?id=7693640
The race condition would be easy to avoid by just having a volunteer operating an account. "IdeasMonthly" would post the thread once per month, with a bit of boilerplate. I'm not strongly advocating for this though - mods are pretty clear about what they think and HN is divided.
I think that there is already far too much pseudo-intellectualism, cynicism, political sniping and dull rehashing of arguments on this site to begin with. You can pretty much predict where threads about bitcoin, self-driving cars, politics or modern web design are going to go, what sort of arguments will be made, and what counterarguments. One of the problems dang warned about when he discussed killing the regular threads was that regularity breeds low quality. This seems to presume some correlation between novelty and quality that I don't think is really borne out by the content here.
I believe that, while dang was obviously perfectly within his rights to do so, this was one case where he potentially cut off HN's nose to spite its face. Surely, if discussing other people's creative and intellectual efforts is an intellectually valid exercise for Hacker News (which is what commenting on submitted links and articles amounts to) then discussing our own, creative efforts is also valid?