>>I had been hoping that Sorgenfri would be Queen Margrethe's new second residence so she can leave Fredensborg to the new Royal couple and their family and the Chancellory could in time be crown prince Christian's home.<<

In a few days Queen Margrethe will be 84 years old. Her 2 residences, Amalienborg and Marselisborg, are probably enough. Sorgenfri will need a major overhauling, regardless of its future use, which will probably take years.

>>The other parts of the complex do remain available for the Royal Family so they might become the home(s) for one or more of Christian's younger siblings.<<


It has already been decided that that CP Christian's younger siblings will receive no apanage so imo it's unlikely they will be provided state funded residences, but you could be right.