KP isn't ready to play C all game, and I don't think it should ever be his full time position.
I'm happy we have Lopez. I think the Lopez/Porzingis/Melo/Williams rotation is one of the best in the league.
Where we need help is the backcourt. Afflalo and Calderon are solid, but no team in the league is a contender without atleast 1 star in the backcourt. Spurs maybe, but Tony Parker is still way better than any backcourt player we have. And they've got a good creator in Ginobli and a strong guard rotation. Parker's production and impact blows away any guard we have. The rest of the top teams have an Curry, Irving/James, Westbrook, Lowry type of player.
If we can get say possibly a DeRozan or a Conley this summer, the Knicks will be very good over the coming years.