Also assuming he is even able to father a child which is not a guarantee.
That is very true.
Don't forget the way technology is progressing very rapidly in this field.
Soon people will be able to order whatever they like in the way of children: a boy with a penchant for science, a red-haired girl, a set of twins!
Designer babies, here we come!
(Don't get me wrong, I'm not saying this is necessarily a positive thing, just that it will be happening with much greater frequency in the future).
Indeed, huge medical progress has taken place in this field - actually, I, for one, believe that, but for this fact, Japan would have had a reigning empress in the 21st century: Empress Mako.
It is to be supposed that there will be even more progress concerning "reproductive technology". But even if there should be I doubt that this will mean that, in the future, literally EVERY couple will be enabled to have a child of their own.
Wikipedia quotes a French study in which it is said that 40% of patients succeeded in having a child during the IVF treatment at the center. Even if the success rate should raise to 60 or 70%, considering the number of childless couples in the imperial family, I would not bet that Hisahito and his future wife could be absolutely sure of being among these 60 or 70%. Besides, I have no idea how many parents with one IVF child decide to have another (and another and another...). But I doubt that there are many of them. The procedure is said to be extremely stressful in particular for the woman and Wikipedia says:
While psychological stress experienced during a cycle might not influence an IVF outcome, it is possible that the experience of IVF can result in stress that leads to depression.
(That reminds me of someone, somehow, incidentally...)
Modern medicine can accomplish a lot but they have to have something to work with. For example, they may be able to save lives that would have been past hope fifty years ago. But they cannot revive the dead, and I doubt that they will ever be able to do that. Regarding the imperial family, I think there is reason to doubt that the "material" they´d have to work with gives anything that would come close to a guarantee of success.
The more I think about the whole matter, the more I would really, really like to get the opinion of a genetics specialist on the situation with the Japanese imperial family.
According to
Wikipedia, the human Y chromosome is particularly exposed to high mutation rates (a risk of mutation 4.8 times greater than the rest of the genome), on the other hand there is a reduced possibility for selection as the Y chromosome does not recombine during meiosis. In other words,
the Y chromosome is exposed to a far higher risk of degeneration than the rest of the genome. I suppose that usually an Y chromosome “beyond repair” would, at some point, simply not get to be passed down to the next generation, either because its “holder”, due to his defective Y chromosome, would prove unable to have any offspring at all or else, have merely female offspring. Maybe this obsession with the male line has, through the help of lots of concubines, so far kept the natural genetic selection from taking its course with the imperial family, thereby preserving a completely degenerated Y chromosome that under different, "normal" circumstances would have been weeded out of the gene pool a long time ago already.
It strikes me as remarkable that already for quite some time before Hirohito´s father, the Taisho emperor, there was but one son in every generation who survived infancy (and inherited the throne) - in spite of the efforts of all those concubines...
It seems to me that even by then there were more princesses born than princes. Of course, there could be a whole lot of reasons for why this was so (at the time many children died early, boys as well as girls), but imo it would be very interesting to investigate this whole matter more closely. It would also be very interesting to take a look at the number of miscarriages in past generations and to know their gender. (Michiko as well as Masako suffered miscarriages.) Of course, it would be very difficult to find out details about imperial miscarriages from Western sources because except in spectacular cases like with Masako they will hardly ever get much public attention if they are at all made public in the first place.
What I am trying to say is that I think it is absolutely possible that male offspring of the imperial family may have less chances to (1) be conceived in the first place, then (2) to be born healthily and last (3) to survive childhood, due to a defect of the Y chromosome involved. Besides, I think it is also possible that the general sperm quality of male IF members may be rather low, due to the same defect. The first would explain why imperial offspring is usually female, the second why some members do not have any offspring at all. Of course, as they all share the same Y chromosome, one would have to explain why in some cases this results in infertility, in other cases just in an inability to father male children. (Regarding Hisahito, I for one am convinced that the sperm got some "friendly medical support", so it is possible that under “natural circumstances” Akishino might never have been able to father a son, either.)
It is possible, of course, that Hisahito will have one or more male children, with or without the help of modern medicine. But, imo, there is really no guarantee for that, not at all.
Government makes plans to honor Emperor Akihito’s cremation request
The Japanese government is making progress on its plans to simplify the funeral ceremony for Emperor Akihito after his request in April to be cremated. [...]
A final decision on the matter will be made by the Imperial Household Agency by next spring, followed by research from government organizations on ways to reduce the funeral costs, in line with the emperor’s wishes. When Emperor Showa passed away in 1989, there were two separate ceremonies held, one based on Shinto rituals and another seen more as government sponsored. This was because of Article 20 of the Constitution, which requires a separation of religion and politics. [...]
By trying to reduce the overall size of the funeral ceremony, as well as holding the two rituals in close proximity at the Imperial Palace grounds, the government, as well as Emperor Akihito himself, hopes to eliminate some of the excessive costs.