Breaking down the rumors here, this is what we got.
It's true that the Inquisition and assassins were cut. Assassins are getting their own update (similar to 4E) which will let them end up in any Imperial Army without necessarily taking an Inquisitor and have some cool narrative missions/kill team missions.This was kind of expected models wise we know Games Workshop loves to sell them and limiting a versatile group of units down to only one or two codices isn't in their business model, no pun intended.
Grey Knights are definitely getting "stripped" of a lot of the bloat they had before, not necessarily the stuff they had. What I mean by that is this codex is C:Grey Knights, and NOT Ordo Malleus.Again with the Inquisitor Codex that isn't a surprise, and if true this could be GW's way of focusing more on Grey Knights in this Codex and less on everything else.
The special characters as rumored at gone, BUT the relics section lets you effectively portray them (functionally) on the table. This lets people convert to their heart's content without conflict as to what is/is not the right way to represent one character or another.This is a little bit confusing but this looks to follow who Games Workshop did Codex: Chaos Space Marine, and how you can kit out and build your own special Chaos Lord or Sorcerer. Surprising yes exciting defiantly.
Draigo makes paladins troops, but they have to be 4 or more models or else remain elites.No big change here, just requiring more models for paladins as troops. No more small squads holding objectives. :/
Crowe doesn't make purifiers troops in the traditional way, but he has a formation that's him with 2-6 units of purifiers in transports. In this formation he gets a bodyguard of the new unit that are based roughly on his "story" per se and is the only way to give him a retinue as he is not normally an independent character.This by far is the biggest changes rumored so far. Yes this follows the fluff but this change forces players to take a formation to unlock purifiers as troops. Mech list are hot again in 7th not as nasty as they were in 5th (remember the Blood Angel mech list?), but none the less this rumored formation will give a nasty addition to any army. Crowe + purifiers + assault-backs with psybolt = fun for all!
Please take a moment to read the full release of rumors here, and let us know what you think.