Joking aside, it's nice to see Carmine and Rosaria getting it on, because it implies that imperial heirs will be relevant to the plot which is very rarely explored. As I've mentioned before, it'd be especially interesting if he ends up with a reincarnator daughter, and he has to balance his daughter's modern sensibilities with the expected duties of a princess (he's literally already promised one to the Gotritoir). It could make things especially awkward if said princess's knowledge made her far and away the best candidate to be the next emperor, as female succession is only just now being made explicitly legal.
Realistically, a three-wife output means he should be able to hold a reincarnator or two in reserve, but there is still the factor of Rosaria's children being "more important" than the others; what if she has only girls, or only has one and it's a reincarnator that now can't be used as a "first-wife princess"? The wives themselves like each other enough to tread into Yuri territory, so we can probably assume they won't try to sabotage each other's children, but that doesn't mean that other nobles will be as understanding. There are many available angles that the author could use for political drama.
All this does hinge on the series maintaining enough popularity to continue getting novels, since these things won't come into play any time soon. But currently, I think it has the potential to go the distance.