He will be Gatti's replacement, a better player, technicaly, tactically, physically is comparable, and has brain. The 25m next year will be paid by selling Gatti (his value is 25m by transfermarkt). Hopefully we can sell Gatti this winter mercato if we find suitors, and get Hancko on loan for this 6 months (+ loan Veiga and/or Todibo as backup). Tactically, Gatti is the most unsuitable player with Motta ideas and Hancko only 6 months older than Gatti(not that old) and he can played as left back too, left footed
If not, we probably will sell Gatti in the summer, but I prefer Hancko more than Gatti if Giuntoli can pull this out this winter mercato (I can see it will improve our push for UCL and Serie A position). Hancko salary currently around 2.35m gross with Gatti get around 2,6m gross per year. Getting Hancko for 2.5 per year +maybe 500k bonus gross if we qualify UCL is still make sense, instead of extending Gatti's contract
If I am Giuntoli, I will tell to Feyenord DS, what do you think about Rugani in Ajax he is impressive right, here take Gatti + Facundo Gonzales and give Hancko for us this winter mercato. He will be impressive with his body and he can build strong brick wall infront of your goal to make sure no goals allowed