They usually never give us the kids
Considering we got an unexpected volume 2 two years later, it might be possible in another volume. Or the mangaka could throw us a bone on Twitter like some others do.
I've imagined it though. I lean towards an accidental pregnancy rather than intentional based on their relationship now; it would still fit in the current story arc but it would be rushed and only a snapshot glance of that future would be possible. Shishikura is definitely the heart and Kotani the brain. But it would be nice for the latter to go all analytical preparing everything and once the baby arrives, he softens up a bit.
And cue Shshikura offering to name a girl Lilia only for Kotani to point out she looks too much like him (S) so they should go with something else.
It was kinda short. I lowkey want to see them have children haha