Don't see how the numbers would work for him or Barca. He's got 3 years left on his contract. Assuming we'd pay him about £350k a week before tax, he'd be at least £30m worse off (£200k x 52 x 3). And they owe him about £15m, so he'd surely want the £45m and probably after tax, so he'd get almost the entire transfer fee and Barca are a quality player less.
Unless he really wants to get away at any price, his options are probably the rags or Saudi, as they're the only ones daft enough to pay the wages