Before the beginning of this year, Alves didn't play as much due to form dip/injuries. Therefore the attack was emphasized and shifted down the left flank. This is why Iniesta was a god on the wings and his linkup with Alba was divine.
That's a very good point. The only thing is, this is nothing to do with Dani, this is entirely down to management. We've seen Clasicos were Dani has been very disciplined about staying in defense and barely venturing forward, in the process he had Cristiano in his pocket.
Dani should definitely be kept, but the management need to be stronger and should be more open to varying their tactics. Switching line ups where Iniesta is on the wings and in midfield keeps the opposition on their toes. Switching lineups where the attacking fullback is left sided or right sided does the same. Also if Alba is injured we can maintain the attacking level with Dani on the right. If we sell him and Alba gets injured, we'll have a lesser attacking full back. Even if there is no injury it can be used to minimise the effects of Alba getting tired.
You don't even need to switch lineups. You can instruct the fullbacks during the game as to how offensive they are.