What I would like to get opinions on is this: Would any of these systems still have HPG's?
My take on it is the reverse, that most of these worlds would (should) never have had a HPG on them to begin with.
I'll try to explain:
I have always operated on the assumption that if a system had population significant enough to be on the maps, it has an HPG, except maybe if it's part of a pirate kingdom or some other special case otherwise noted. Most of the worlds in question start the Succession Wars under Liao, Marik, or Taurian control and I would expect them to have HPG's at that point.
The Arano sourcebook makes a commendable attempt to reconcile the HBS game's depictions with mainline BT canon, but for the game to work the tech level out there in the boondocks had to be orders of magnitude beyond what it had any right to be by established BT canon for the periphery.
The existence of HPGs out there is one such thing: They simply shouldn't be there for all we know.
Up until the Arano book, the periphery border was pretty much defined by the HPG grid. Worlds with a HPG on them were typically considered Inner Sphere worlds; worlds without their own HPG but within receiving distance of a HPG were considered near periphery; and anything beyond the reach of HPGs was deep periphery.
But then the HBS game and then the sourcebook basically established that the HPG grid extended into the Aurigan Reach region.
(Yes there always were exceptions. Some Inner Sphere worlds don't have HPGs - never had them in the first place, others had theirs destroyed. And a couple of notable periphery worlds, namely Oberon VI, actually feature a functional HPG station. But nothing even near to the level we see in the Reach.)
I had some very minor input during factchecking, including some tidbits to the overall depiction that might point towards a possible explanation: ComStar maintains the Rimward sector HQ of their Explorer Corps at Hellespont, and it would make sense if they had a HPG link to that HQ. So maybe there's a tendril of HPG links extending from the Inner Sphere through the Aurigan Reach all the was to Hellespont. The Aea writeup specifically mentions that the world is probably only inhabited at all because it has a HPG that is still staffed.
And remember how HPGs work: They "jump" radio waves. You can send messages to anyone in a 30ly radius (50ly for Class A stations), you don't technically need a HPG to receive a transmission. So that tendril of HPG links is at least 60ly wide.
When we could assume the reason they disappeared from maps is that there was no significant population left there, it's easy to imagine ComStar closing up shop. However, the Arano SB indicating that they aren't totally abandoned makes things more problematic for me. [...]
So at what point does ComStar make the decision a world is no longer significant enough to have an HPG and pack up? Or do they stick around until the bitter end just to maintain their benevolent image?
I don't think ComStar ever voluntarily shut down a HPG. They were invaluable infrastructure for colonisation efforts, even smaller Class B stations can create a HPG bubble 60ly across. That is, in my opinion, why the HPG grid and properly colonized space align so precisely. (Except, of course, in the Aurigan Reach.)