Not worried at all. Seahawks can survive 2 games without Miller. The Seahawks survived worst against better defenses than the ones coming up, last year, @Hou and @ Indy. Seahawks were without Miller, Okung, Giacomini, and Unger for those games. They still went 1-1, and really could have won or lost either games . Those games were also consecutive weeks of 10 am starts where the next two are MNF and a home game.
I expect the O-Line to come out much stronger overall... 1) Because they're all healthy 2) Okung probably was able to catch up on his training/conditioning over the last two weeks and 3) Britt also had plenty of time to sit in the class-room to dissect his weaknesses thus far with Cable.
Also, Luke Willson is a big boy, now, 260-265, he stepped up when needed last year, and I think he'll do the same. He'll make some plays too with this opportunity especially in the next two games. Redskins and Cowboys don't have great middle defenses, Willson should have chances to blow the top off the seam in the next two weeks.
There... little bit of optimism.