Well, the only two really concrete links have always been Menez and Nainggolian.
With Nainggolian we face competition from pretty much everyone in Serie A, and I don't think we want to get caught up in a bidding war, especially if other teams, such as Napoli or Inter can be assumed to have more funds than us.
About Menez I still hear rumours, but I think that in january a pre-contract will be signed and he'll arrive in July.
Don't expect any big signing in the winter mercato, there has rarely ever been one. On top of that, we're doing very well domestically, and probably won't buy anyone for the sake of EL. It makes more sense to look for serious reinforcements in the summer, when there's more time to negitioate a fee, and more time for the player to settle in.