I seriously doubt whether Wenger is inclined to pull out the cheque book for a striker despite Giroud's injury.
I think he's banking on Sanchez being able to adjust fairly well to a central role and the team being able to get by in that transition period. But from any kind of objective standpoint, it doesn't look like an attacking line-up that can mount a title challenge.
Sanogo and Campbell are both still raw and inexperienced.
Podolski is very one-dimensional although his god-like left foot is nice to have.
Oxlade Chamberlain is an exciting player but needs to add goals to his game.
Walcott will be great to have back, but with Giroud out for so long, it seems like while with one hand the injury gods giveth, with the other they taketh away.
Another body in there, of even a decent level perhaps not even as good as Giroud but at least more experienced than Sanogo would have given the team the nexessary depth. It makes you wonder whether Arsenal really are serious about taking on the title this season, but surely Wenger must want it more than anyone. I don't know. In the end you just have to have faith I guess from match to match, rather than dwelling on the big picture too much.