Thinking about the idea now it would seem impossible to translate this into a film or TV adaptation given that there may be budgetary and technical boundaries but if such a translation could be and is possible to do then here's my idea on this
The whole story would be spread across six films like the Star Wars series and the plot could be adapted from these 4 literary sources attached to SMAC:
Done rightly, I think this series could evoke the feeling that this is "Star Wars meets Avatar meets Firefly meets Game of Thrones" which does sound like a bit of a bold and ambitious statement; if you want to appeal to the "average soda slurping, action minded moviegoer" then maybe make it have the feel of The Dark Knight or No Country for Old Men i.e. full of action and suspense yet filled with great in-depth characters, a gritty dark neo-noir atmosphere, believable romance and philosophical themes
As for cast, I read through this as well as thinking about it myself and I have come up with the following member ideas:
Now just to clarify, the reason for the inclusion of old and young versions of the same character has to do with what may be the story's structure in that Journey to Centauri would be woven into the main plot of Centauri Dawn, Dragon Sun and Twilight of the Mind possibly as flashbacks which give the young cast members ample screen time as their older counterparts
I actually also think this series should be co-directed by various directors one per entry in the series like James Cameron does one entry, Steven Spielberg does one, etc
This is just my opinion though on what the movie should be like should a project like this come to fruition. If only Sid actually had someone propose the idea to him and see what he does with it - either he could turn it into a TV series or a film series.
PS If the idea of weaving in a prequel to the main plot is a bit too fidgety and stupid then maybe the events of Journey could actually be more like a TV mini-series and Centauri Dawn, Dragon Sun and Twilight of the Mind could just be the main entries in the film series with original stories featuring the SMACX factions as a sequel series if initial series is successful