Arsenal really need a striker, Giroud just don't cut it, scoring 1 goal in something 6 games isn't acceptable. I feel Arsenal need to buy a DM, to put some pace in the midfield. They will also need a new RB, and GK due to Sagna more than likely leaving and Fabianski leaving.
I think Arsenal will buy a striker, there are already rumours that Arsenal have signed a 21 year old striker called Josip Drmic, he has a pretty good goalscoring record this season, (15 in 26). I would also like to see a world class striker here too, preferably Costa or someone similar, maybe even Balotelli seeing as he wants to leave AC Milan and he's sponsored by Puma, the same company Arsenal will be sponsored by next season.
I think Arsenal will sign a DM, who yet I don't know, Lars Bender would be a good signing and he could slot in alongside Flamini, maybe we could even sign Kallstrom and keep him there, I like what I saw of him against Swansea (despite it only being 10 minutes ) Also, slightly off topic, I can Arsenal being linked with Draxler again this summer, who would be a great signing.
As for RB, I think this might be of them positions that Wenger will not strengthen but will only weaken in the summer, he'll probably sell Sagna and not sign a replacement, Wenger has a knack for doing that. As for Goalkeepers, I would probably take Viviano for another season, so this way Viv could at least get games in the cup competitions.