I don't think he will feature against Arsenal at all. He is short of match fitness and it is highly likely that Moyes will set up to stifle Arsenal rather than attack them. This has been pretty evident in all of our games against the traditionally top clubs this season and is likely to continue against the in form side in the league. Valencia will get the nod for one of the flanks with Adnan the other if we indeed try to play with some width at all.
At this moment in time, Nani's future is far from certain. He is yet to complete 90 minutes for us; play in the Champions League; and is seemingly lower down the pecking order than both Adnan and Valencia. With this being a world cup year, something is bound to happen as the player will in no doubt begin to consider his chances of representing Portugal should they qualify.
I know the gaffer keeps harping on about utilizing the squad but the signs are there with regards to the squad status of various players, including Nani's.
I have always felt, Nani could flourish in a side like Arsenal's or Spurs given their general approach to the game and preference for specialized full backs even when short of numbers.
Unless the situation changes, I wouldn't be surprised to see him moved on either in January or next summer.
I must confess, I am a huge fan of Nani's style of play; what he offers; and have never bought the usual rubbish labelled against his him in terms of his consistency, decision making, bravery, etc. Sadly though, I don't think the most important person at the club shares a similar take on his ability. Fair play to the guys who make the squad in his place, though I rarely get what they offer different from him (Adnan excepted).