IMHO, since the setting has been out of print for a while I would just start from scratch and use what I "the author" wanted to use from the old info. I would not worry about this or that unless you have all of the past products and do a through work-up of how each product advanced the timeline and state of affairs.
If you are going to do it then do it whole heartedly and not halfheartedly. IE do it or do not, there is no try.
MDC
Indeed. The first thing I would need to do (assuming that I am taking this thing on) would be to go through all the old background material as an editor and clean it up. It has been so long that I would almost be seeing it with fresh eyes (and who was that Alexander Brooke Lindsay anyway?). And then advance the timeline. I can definitely see houses starting to want to break off, and Kulthea/CerilVII might be a crucial moment when the Emperor, the Dia Khovaria and the royal houses come to a crisis point.
I would suggest to do as markc said: Do or Do Not, there is no try.
As other mention, I would suggest to take ALL the material, polish it, reconstitute, resurrect, then worry about rewriting it. I tried to do the same with my old campaign world of Udava. However, I found as a single person, I could not do it. Especially when considering there was over 300GB of data (spread across about 200 CDs and DVDs) for me to attempt to sift through
by myself. I was forced to abandon that project and perform a complete rewrite with a whole 'nother world I have dubbed Onaviu.
If you need help, I would be willing to aid. The choice is yours.
However, I do not possess all the needed materials due to the murder of my wife and daughters and losing much of my RPG library due to recuperating from that crime.
As Wolfhound said:
Terry, that sounds like a good approach to take to me. Would be great to see products based off of a slight advancement in time with those types of added stresses to the political landscape.
Another suggestion would be to have a couple of areas of space that break off from the Imperium as more of independent groups that are not associated with any major house but that are only semi-organized (would be a good location for pirates or freelancers to operate out of or the likes), or possibly some areas that are out past the edge of the Imerium where things are still a bit on the chaotic and lawless side (kind of an old-west/sci-fi type of setting along the lines of the outer planets in Firefly).
I also agree with yammahoper that a product like an Imperium Master Atlas would be a fantastic resource.
rmfr