They are changing 40K to slowly. But it is done in a much more careful and much more believeable way.
I am not really that hyped on this psychic awakening, since that is supposed to mean DOOOM! in all the earlier fluff. But now it is coming and everyone will be involved somehow.
But I hope it does not mean that all that is familiar is removed. And in the end, I think that will not be the case. GW shock the galaxy to the core with the great rift through it. Also, they are finally giving us true scale marines and yes, they probably needed some change. After all, the Marines are the flagships.
We shall see what they do to the Guard, however. The Guard REALLY need new miniatures. Really need them. They clearly seem to have decided that the basic concept of the Eldar is still good so they work around it creating new cool stuff. But they really need to give us a new baseline of guards, and clearly it is the Cadians that will remain that one. And the Guard is a popular army, and people love their mighty backward looking tanks. They created new characters for it in the shape of for example Severina Raine so the concept of the poor bloody infantry is something they seem to understand have a strong pull.
If you want to be over the top superhumans, the Adeptus Astares are where you go. If you want a more recognizeable feeling you go for the Guard. And soon you can focus on the more fanatically zealot side via the Sisters of Battle.
If you want something more like a modern style army with discipline etc you have the Tau giving you decent humanoid elite soldiers. You even have the option of saying they are humans loyal to Tau. Firepower first concern, overlapping fields of fire, breach and clear etc. All you may want if you are into a futuristic versions of modern soldiers.
The list goes on and on. 40K have managed to find something that can appeal to everyone and it does not really conflict that much. You have it all from magic, psyker dominated armies to high tech futuristic stuff that do not care about psychics and everything in between.
Somehow I think they wanted to get away from the "real world" to avoid ANY potential PC issues and to be able to copyright everything.
But for some reason GW do not want normal people to have any real place in AoS. They went for the He-Man idea all the way.
