Prince Carl Philip' and Princess Madeleine's children will still be Princes/ses and Dukes and Duchesses, but they will not be styled HRH. I wonder if a future wife of e.g. Prince Alexander will become a Princess. Nothing is said about that in the announcement from the Marshal of the Realm.
According to the Marshal of the Realm, the princely titles will be regarded as personal. Future spouses and children are not entitled to use those titles.
RW1