Considering the people who keep bringing up the sex question, could you imagine the furor over the possibility of a child?
Not going to happen. Especially with Kieran behind them.
No, I think story reasons was just code for him being old and very elfy and thus relevant to the story, so it would make sense.
True, but considering that the first installment in the series had a possibility of performing Dark Ritual and conceiving of a child (even going as far as convincing female Warden's lover to do the deed with Morrigan), it wouldn't be something that's without precedent in the series.
They've also not shied away from giving Morrigan an arc as mother to Kieran in OGB world-state (with it likely being a catalyst for her to change and accept Mythal's plan to be her inheritor, even if only for the sake of her son) and it seems to be something they plan to expand it further in the future - question is whether something similar would be repeated in case of Solavellan?
Like I said, I'm unconvinced, but I can't think of anything else as of now - and Solas being elfy and old doesn't really smack of "super story reason" for me, especially if we don't even know if the 'ancient of anciest elves' even really care for gender much. But who knows - I suppose we're yet to find out what exactly they mean by this.