Prince of Orange to become King Willem-Alexander
When Queen Beatrix abdicates, His Royal Highness the Prince of Orange will become King Willem-Alexander, and Her Royal Highness Princess Máxima of the Netherlands will become Queen Máxima.
They will both be addressed as 'Your Majesty'. After abdicating, Queen Beatrix will be called Her Royal Highness Princess Beatrix of the Netherlands, Princess of Orange-Nassau, etc. As soon as the Prince of Orange ascends the throne, his eldest child, Her Royal Highness Princess Catharina-Amalia, will be the first in line to the throne. She will then become the Princess of Orange (under section 7 of the Membership of the Royal House Act).
The titles and names of the other members of the Royal Family will not change after Queen Beatrix's abdication. The membership of the Royal House and the line of succession will however change under the above Act.
After the abdication, the line of succession will begin with the children of His Majesty the King: Her Royal Highness the Princess of Orange, Her Royal Highness Princess Alexia, and Her Royal Highness Princess Ariane. The next in line will be His Royal Highness Prince Constantijn, his children and finally Her Royal Highness Princess Margriet.
After the abdication, the children of Her Royal Highness Princess Margriet of the Netherlands and Professor Pieter van Vollenhoven will no longer be eligible for the throne. They will also cease to be members of the Royal House.