Eh, I'm inclined to do the reverse. Calian being the foolish boy king makes about as much sense.
That's why I kind of want to give him a pass. Bioware already piled on his 'negatives', making him a complete kingly blunder [ie: shooting blanks on top of it all] would feel like overkill. Especially since for all his naivete and immaturity he seemed to be rather genial and nice.... like a puppy.
Of course, even if Anora isn't barren. She's kind of problematic no matter which way she turns.
Her other marriage match is a Grey Warden.
Worse, she won't take a suitor if they both don't marry her.
Indeed, which likely means Bioware was setting up a succession crisis for future use. And failling that, if they don't want to do anything with it, they could just have another one of Maric's illegitimate children, or even one of Cailan's unmentioned ones, pop up and fill the void later on.