Hmmm. Given the ready availability of the 2004 edition second-hand, and the relatively low sales of the non-
Troubleshooter elements of the 2009 edition... maybe the game is functionally complete and should be left to rest for a while, from both a business and quality-level perspective? I'd love the game to get more attention, but more low-selling supplements is not the way to do it.
I know what *I* would do, supplement-wise, but then I don't have several years of bloodthirsty experience in the RPG market so my opinion may not be valid...

One supplement a year full of mini adventures, drop-in locations, bits and bobs of content from previous editions that has yet to be reused, et cetera. An Annual, if you will, in the spirit of
Acute Paranoia.
This "splatbook" approach works great with
Paranoia where, in all honesty, you don't need massively long adventures / location books, since fine-grained detail is not really part of the game. But a yearly book of goodies to drop into ongoing games... oh and of course to include content for the
Internal Security and
High Programmer sublines to drive a few more sales... maybe even interviews/opinion pieces from some of the games designers, GM staging tips and so on.
If a commitment to one supplement a year could be made, I think this would be the path to take.
Possible names for such a series:
The Paranoia Annual (keeping it simple!)
Chronic Paranoia (a reference to Acute, natch)
The Incomprehensium
Chapter Redacted (with a polite not to Games Workshop's legal department)
I really ought to finish the three half-complete Signs & Portents submissions I'm still tinkering with and respectfully submit them for consideration

Actually that's another thing that could be included, stuff that was only in S&P before, or stuff still in the queue pending the eventual relaunch.