According to Scotsman.com

after her marriage [to Prince Charles], Camilla Parker Bowles will become the most senior female royal behind the Queen. As HRH Duchess of Cornwall, Camilla will take precedence within the Royal Family as the wife of the Prince of Wales and heir to the throne.

But unlike her sister-in-law the Princess Royal, her importance solely relies upon marriage.

She will have no constitutional role but will be invited to state and national occasions at the Queen’s invitation.

She will not be known as the Princess of Wales, a title which for many people worldwide still conjures up memories of the Prince’s popular first wife, the late Diana, Princess of Wales.

When he becomes King, she will be known as Princess Consort.

Conjures up a great image, doesn't it?