Not a novel reader, and I would loveee if there really was mpreg, but I interpreted that line to mean that just because there hadn’t been succession issues in the past, that didn’t mean they shouldn’t worry about it occurring in the future.
Like the people might challenge the king’s chosen heir’s right to rule
SPOILER Σ(  ̄□ ̄||)
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Yes, there is implied mpreg. It’s through the use of magic in the form of a cocoon after an intimate moment together. I only say implied because of where the novel is at rn on Tappytoon. We haven’t seen the baby yet (I can’t say more without further context to spoil more than asked) ;_;

To all the novel readers, does the mc get preg? Okay I sound crazy but maybe there are some powers and then they make him be able to be preg? Cuz in one of the moments he said that ‘Just bc something doesn’t happen yet, doesn’t mean it never will’ Like that is def a foreshadow of something.