Not one for fully trusting in the rumours that get thrown about on various forums but apparently this source is quite reliable and informed. So I figured it was worth sharing. If there is any truth to it we are in for some exciting times in the near future!
"Anyway, on topic, the list of possible new armies I was given:
World Eaters NOTE: VERY LIKELY AT SOME POINT IN TIME.
Various other MAJOR chaos factions devoted to a single god. (All Undivided perposedly going to be represented by the Vanilla codex which I hear is next up to be started on.) I hear they want to actually do a few over the next 5 years.
Dreuger (sp?) (Squats) NOTE: NOT VERY LIKELY AT ALL, it was discussed from what I hear though. I only mention it because I know it would come up if a discussion formed.
Note that no plans are currently being formed for additional marine chapters as far as my source knows. (Outside of the ones allready released and which need to be updated, of course.)
They definitely want to do chaos factions, the rest is up in the air. I suspect they have plans to start on World Eaters.
At this point, I am fairly dried up in terms of what I got"