I have absolutely no idea how accurate this video is, so please take it as rumor and not fact. But I found this video bouncing around on Reddit and *IF* it's true, AoS 3.0 is going to be massively different...
Basic rundown is that battalions are supposedly being changed to be more free-form and have less specific unit "taxes" to make them better balanced across all factions. Could be good, provided that their effects are good and not super-generic.
Buffs and penalties are getting the 40k treatment and are capped at +/-1. Mystic Shield is changing to be +1 to save instead of re-roll 1s. Meh. Some armies are annoying with stacking penalties to hit or bonuses to save, but it's not really game-breaking. No word on if this means than rend is included in this limit or if it stacks with the -1 save penalty cap.
Charge reactions: when your unit is charged you can spend a CP to either:
Hold: +1 to save.
Stand and shoot: Overwatch with a -1 to hit.
Fall back: d6 movement, but only if you were charged from within 9 inches.
Sounds like a big buff to shooting, as a 40k-like overwatch rule just means that there's little to no reason to not have shooting units over melee ones. However, it also buffs armies with big charge bonuses like Orruks and most of Chaos, as you're opponent can't run away if they're charged from outside of 9in. This will probably help with the rumored smaller board sizes, as otherwise the game turns into a 40k 9e melee fest once again. However,CP are going to be more important than ever because:
Probably one of the biggest changes: CP is supposedly changing to work more like the OBR bonus points where CP resets to 0 at the end of every battle round and is accumulated again at the beginning. So basically a *massive* buff to going first, although the double-turn is still probably a thing. If you go second, you're basically getting hit all through your opponent's turn with 0 CP to react to anything. Unless they change it so that CP is accumulated by both sides at the start of the battle round, not on your turn, this really makes going first more appealing than hoping to get the double-turn in a lot of situations.
And finally, whoever goes second in turn 3 gets to remove an objective of their choosing from the board. This seems weird. The guy doing the video was saying it was a direct response to how many games ended due to the priority roll for turn 3. Which does seem to often decide the game, to be sure. But it seems that GW is really trying to encourage stretching games out for the full 5 turns.
Again, 1000% rumor. Just thought it would be interesting to share.