Don't think Mikel's passing is incisive enough to play at 10, nor does he have any real pace which I like in forward players. I think he's fine where he is, and has dipped due to overexposure and asked to play a far more ball-winning role than he can, but I love him as a constant outball and deep playmaker.
I think 352 would be too adventerous right now (although funnily I think we're better built for that formation given the players we have - lack of true wide options, all our forwards being better/wanting to lay through the middle), but until January I'd just play deep and on the counter with 2 of Poldi/Theo and Giroud up top, and Cazorla on the wing. Arteta/Caz are fucked basically, neither can realistically not play until we get new signings in.