I don't see any possibility of Wenger playing 4-4-2. Maybe in the last 10 minutes needing a goal.
If you put Sanchez and Giroud up-top and play Ozil and Ramsey and a DM than you don't have place to put two wingers in and it becomes a very narrow diamond 4-4-2 which doesn't work at all. (Anybody wanting one of Sanchez, Ozil and Ramsey to be dropped at the expense of Giroud clearly works for his PR team)
Sanchez is the striker. Hopefully we can get another big name and Giroud can pack his bags.