Well, we already do have a better LB in Santos. Gibbs is OK at 2nd choice, I guess. My worry with him besides his superhuman ability to break down if someone breathes on him is that he's frankly a poor defender. He looks too much like a winger being pushed back and having little idea of where to stand. He has until the end of the season to prove himself, but I think that Wenger will keep him on anyway. If it were up to me, I'd sell him and give Coquelin the minutes as he genuinely does have a defender's brain, and has done bettter going forward in his limited appearances than I thought he was capable of.
We should definitely release Theo. Podolski/Miyaichi on the LW, then Oxlade/Gervinho on the right. Only reason I can see for keeping him is that he's Robin's mate and that at 22, he might still 'come good', but he's cost us for years now on the wing and simply because of that, he doesn't deserve a pay rise. Let him flourish at a long ball side. I do think teams like Liverpool and Newcastle would be interested in buying him. Another quality winger would be nice (so as to permit Miyaichi to have another loan spell), but that's probably asking for too much.
Don't see the purpose in converting Song into a CB. We already have 3 perfectly good options there, and then the likes of Djourou (who I don't really rate - but he's signed a new contract so he's definitely not going anywhere) to come in if need be. If things get really bad, then Song can drop back, but I'd rather he just plays as a DM, and lets the more talented players go forward.
As for Podolski, he's played quite a lot at LW, so I don't see any massive learning curve bar the obvious transition from the Bundesliga to the Premier League.
EDIT: Forgot that Gibbs is a home grown player. That's probably the only real use he has, unless he needs to be registered now that he's 22. Does Coquelin count as a HG player? If so, then I guess there really is no purpose to Gibbs after all.