Up until last year I'd have happily sold Coutinho to buy players that are better suited to more traditional roles. He is too slow out wide and was very wasteful in the centre of the park. I often felt that his presence (although capable of brilliance) was detrimental to our overall game.
He really stepped it up last year and his strengths now far outweigh his weaknesses. He has the ability to completely control games and he is fucking wonderful to watch. Panache!
Even If we sold Coutinho I doubt Klopp would sign another striker or winger to replace Firmino, Salah or Mane in the starting 11. He obviously likes Lallana so we'd likely look at bringing in a top quality Cm ... which is what we are trying to do with Keita and that's without the loss of Coutinho.
So, if we sell Coutinho...the likely result is Lallana filling his spot, a bucket load of cash that we can't spend and someone like Mahrez getting shoehorned into AM or on the bench waiting for Mane or Salah to get injured.
In conclusion, selling him is pointless.