By mid 20th century most royal lines around the globe were gone. The few that survived (Spain, Netherlands, UK, Belgium, Japan and so on) managed to survive by signing away most of their power to a constitutional monarchy system. There were a bunch of sad stories, mostly the french and the bolchevique revolutions. The last Louises (16 and 17) died in the most gruesome manner, as the Romanovs. I get why, at the sight of the rebels, the royal families had to die: to leave them alive was to incite loyalist and undo the (much needed) reforms.
But there is another story of this sort: the remarkable tale of Puyi of China. Anointed and dethroned as a child, he never was an actual threat to the reforms. However as an adult he tried and failed to gain back his crown. When captured and court martialed, Puyi was given the opportunity that the Romanovs and the Louises never had: he was to live, grow and become his own person, not as an emperor but as a citizen. If the pinnacle of the former nobility could appreciate the new regime, there would be no clearer sign that the rebolution was righteous.
And so Puyi survived the trauma of being the last of his royal line and died being 61 years of age, reasonably happy and drama-free.
What makes me think is that Puyi had the chance to see the rot of what imperial China did to the populace. Louis the 16 could see the state of France when it was too late, and his son was too vulnerable to survive on his own.
Source: reddit post