It depends on how badly the source of the collapse wants them dead. The Japanese imperial line hasn’t changed since before the Meiji restoration. The Hapsburgs are still the monarchs of Europe and one of the most wealthy and powerful families in the world. Hell, le ancien regime had to be overthrown several times before they stayed out of power.
Also there is no meritocracy in imperial collapse, there are skills that lose value and skills that gain value, but it’s not as though it’s some reset, it’s usually warlords and demagogues. It’s a time in which the cunning and brutal succeed over the honest and efficient. It’s the era of Julius Caesar not of Ramseses II.
Complete purges are rare. Usually usurpers will marry into it to legitimize rule. And even when they don’t it’s usually the worst (moral) middle class/lesser nobility/military leaders to take the reins. To our knowledge one servile war has succeeded and doing so has left a nation impoverished to this day.
Kind of weird to call out Haiti specifically in this situation, especially considering all the ratfucking they went through at the behest of the imperial powers.