@saab,
saab wrote:The future King and Queen I would use because they are already choosen by birth,
We can use "the future xxx xxx" when we are writing, in the present, about someone in the past, who we already know will later be a president, world champion, king, etc. That is why they are of interest. This is perfectly normal English usage.
Jones' look at Hitler's formative years provides a startling and insightful picture into the future Fuhrer, examining his career as an artist,
Baba Sy was in great shape since he had won his first 6 games - something that remained engraved in the mind of the future world champion Tonny Sijbrands.
...boats that likely transported the future Colonel Parker to America...
Also, it is never certain who will be a King or Queen until the succession happens. Birth is not sufficient guarantee. Princes and princesses can die. Kings can abdicate as in Britain in 1936.