You're right, and wrong!
Correct, he's club trained, which is fantastic for the club, and exactly what we need to continue to produce.
However he won't need to be registered for next years squad either, as he'll still be young enough to be exempt from the squad rules. The measure for if a player is young enough to not be required in the 25 man squad is if they are 20 as at 1st January of the year the season starts. So, for this coming season, the 2015/16 season, Denayer was 19 on the 1st January (his birthday is June). That means for next season, the 2016/17 season, Denayer will have been 20 as at 1st January, so still young enough to not be required in the 25 man squad. Lopes is the same, he's still 19 but turns 20 at the end of December, so will (just!) be 20 when the 1st January comes around. The first season either would need to be included within a 25 man squad, for either the Premier League or Europe, will be the 2017/18 season.