Dînadan:
GW have announced some of the changes that’re coming in 8th ed 40k:
http://www.beastsofwar.com/warhammer-40k/coming-new-rules-death-guard/
Taking a cue from AoS, they’ll be introducing a three ways to play system - open, matched and narrative
Thematic armies - taking thematic armies will net you bonuses (we already have this to a degree with things like the bonuses from formations but this will be even more bonuses from the sound of it)
Movement values - they’re bringing movement values back so things don’t all move the same distance
Armour modifiers - weapons modify saves now (no idea if this replaces the current ap system)
Charging - chargers go first in combat
Leadership - they’re scrapping the current rules and instead you roll d6, add the number of casualties you’ve taken then subtract your ld to see how many extra casualties you take. From what I gather this replaces the current breaking from combat/fleeing rules.