The offensive "identity" wont' change. Edelman will be expected to do his job, which was previously Wes' job and the gameplans and playcalls will continue to be made based on the opposing defense. They wont run if the defense is stacking the box and they won't force the pass if they defense is dropping everyone back.
And it's not like the spread is new since Moss/Welker got here.
Moss has been double teamed every single game for most of his career. No matter what you want to say, Moss being on the field will be a big factor. I fully expect him to make plays, even the best defenses don't contain Moss over the longterm. His "bad" games this year came in games where Brady missed signficant practice time and was running plays for the FIRST time during the actual game, along with other things. Defenses have to do all they can do just to keep Moss' numbers human, but he'll still produce.
And this ridiculous assertion that Brady only looks for 2 guys has got to stop. Losing Welker is not GOOD for the team, although I think the team can overcome it. There is no "blessing in disguise" here, I'm sorry. But just look at Welker's production. Look at Brady's production, even with all the injuries and the toughest pass defense schedule in a couple of decades etc...