It depends what you mean by 'realistic' as a club we have money so we could go out and buy someone World Class should we want to.
Its all about how conservative we are or wether we are willing to spend.
Players we've been linked to..
Adrian - Our most likley option. Skillful little player but a poor goalscoring record. (I'm not convinced, seems very lightweight.)
Ba - Looks to be going to Chelsea though. Is he really any better than Giroud? (again.. not convinced)
Jovetic - Im sure could be tempted to leave Everton should a decent offer come in.
Llorente - Llorente wants out at Bilbao and only has six months left on his current contract (meaning Bilbao will most likley sell him in this Window so he does'nt leave on a free)
Benzema/Higuaine - neither are first choice at Real I would imagine both are bored at taking turns coming on as a sub. Wenger has admitted an interest in brining Benzema to Arsenal in the past. I also think he's perfectly suited to our style of play.
Cavani - (Super unlikley) Would cost a small fortune so unlikley but the guy is a TOP talent and still at a relatively small club. He will be looking to move. Would be a great signing though.
Holtby - Liked to Spurs. The Schalke AM as been fantastic for the last 18 months. Not an area we NEED to strengthen though.
Luke Shaw - Looks a quality talent. Fairly likley we will go in for him. Already better than Gibbs at 17.( IMO.)
M'Vila - Exactly what we need. Only problem is his attitude. Big, aggressive and technically top notch. Has fallen out with his current club.
Lucas Biglia - Could be a bargain. Simular to Flamini but with more flair.
Oh yes ..its a slow day at work.