yes, injuries mean a big problem for Napoli. I hope the Belgian player doesn't have a long injury period. He couldn't be in the squad for a long time because of this problem he had at Manchester City. Since he is 33, there are a few years to be productive. In order to be productive in these few years, he will need to play without getting injured. I hope it will be a useful transfer for Napoli.
De Bruyne's arrival at Napoli should not need much time to adjust. De Bruyne is used to the fast tempo of the EPL. As for Serie A I think it's a little slower. Maybe De Bruyne just needs to adjust to the strategy used by Ancelotti. I think MLS and Arabia have made big offers for De Bruyne but he seems to want to stay in Europe. I even read in the local media that Barcelona are also interested in him, but it seems Napoli are more serious about his future plans. I hear the two-year contract still has an option to extend it by one year.