via BoLS 1-27-2014

Launch Window - @September
Rules Summary: Updated Mini-rulebook contains FAQs, minor tweaks and clarifications, and much of Stronghold Assault rolled into a new shiny package.
Miniatures included: @70
Armies:
Blood Angels (plastic quick assembly)
- Assault Marine Squad
- Tactical Marine Squad
- Death Company Squad
- Captain (kitted out for assault)
- Chaplain
- Sanguinary Priest (limited edition, similar to the Dark Vengeance mini was)

Orks (plastic quick assembly)
- 'Ardboys (full mob)
- Nobs (small squad)
- Warboss
- Big Mek
- Ork themed fortification

This was described as simply an updated Warhammer 40,000 Starter Set and specifically "NOT 7th Edition."
You will note that September falls right smack in the middle of the rumored release slots for Orks (a couple of months before), and Blood Angels (a couple of months after). 

On first glance the "not 7th Edition" makes no sense until you go back and read this. This could certainly be the start of GW rolling the "organic living ruleset" for 40K that does away with edition numbers and the sales dips they cause. Instead we would get updated core products such as rulebooks and starter sets from time to time to "bring them up to speed" with all the most current rules additions that have been rolled out in the intervening years.

This rumor comes from high-confidence sources.