I'm more exited for a complete game overhaul because the one thing 40k has been missing durin 5th is real character. With everything streamlining and less choice, im looking forward to a time when the battlefield becomes an integral part of the game, not just an extra save. Why in this futuristic sci-fi universe does every battle take place in verdant meadows, the streets of vogon, or on a dusty desert outpost? i want a rule system that inspires me to play games of mighty heroes battling in alien worlds, where the unexpected may shift the game balance, and the most ingenious commanders will win through adversity.
Players should be rewarded for having varied and wild forces, not photocopied meltagun toting hexagons.
But just to lay my cards on the table, 6th won't be that drastic. As a rule of a thumb, if it seems like a leap from the last couple of codecies, then its unlikely to be in 6th.
Mechanics might change, but they wont be replaced/removed.
For example, AP might reduce armour, and have an effect in cc, but it won't be replaced by an alternate system. I don't see cc weapons gaining strange and personalised AP values, but pistols using their existing values, I can believe. Maybe ccws will gain a sweeping AP value, but not individual to each weapon type.