> [When this comes to pass,] the emperor system, which depends on an unbroken line of male heirs, will collapse.
These two statements seem to be in conflict.
> What is striking is that 74% have no objection to the offspring of a woman emperor succeeding to the throne. If this were to happen, it would be an historical first.
Women have succeeded to the throne, but they have been succeeded in turn by offspring of an earlier male emperor. Every emperor (in theory) has been able to trace their ancestry back to the sun goddess through the paternal line.
Tracing ancestry through the maternal line as well would be a significant change.
> paternal line
Hmmm.
I mean, I guess it depends whether you count her sons as the first generation or not, but still, why would deity-ness (is there a better word for this? Deism?) pass from her to her sons and thence only to their sons?
> On some occasions [of a reigning empress], the direct male heir was only a toddler and unable to perform the imperial rituals. In such an instance, his mother, aunt or elder sister, if also of Imperial lineage through her patriline, temporarily took over the throne until the child came to puberty, which was deemed sufficient for a boy's accession. An empress' offspring also did not have claim to the throne from the said maternal lineage, so assigning a female to the throne had the convenient effect of postponing succession disputes.