De Bruyne can still have a big impact for Napoli, Conte job will be much easier with De Bruyne in his squad. Serie A is not as competitive as the Premier League, so De Bruyne seems to be able to adapt easily and quickly. Napoli efforts to defend the Scudetto next season will actually be a little easier, because Inter Milan don't seem as strong as last season after changing managers
If opponents of Napoli give him time and space, with a ball he will be able to make many assists and dangerous key passes for Napoli. At an old age, De Bruyne has abundant experience and he is skillful for playing more cleverly while maximizing effects, though his body will be biggest setback that he need to win against himself and his physical body first.
There's no a better thing than getting KDB as a free agent.
It's a win win situation for him and Napoli. However, his injury prone may be the problem, but i think he's already getting rid of it.
It's truly a win-win cooperation between De Bruyne and Napoli and his performances for Napoli next season will be very interesting. I believe that if De Bruyne has good fitness, he will have considerable contributions for Napoli but whether he will have it in a next season, we will have to wait for it. Only time in a next season can help us knowing about it, and it does not mean anything by speculating about fitness and contributions of De Bruyne for Napoli while these factors are unpredictable especially with an old player.