I think you may be getting thrown by the article's admittedly weird use of the word "subgenre"? It's not talking about sales of romance v. romance with wizard stuff. It's referring to "romance" as one subgenre of fiction, "crime and mystery" as another, etc. It's not talking about subgenres of romance. For what it's worth, I think paranormal romance does sell pretty weird and would generally be classified under romance, not fantasy, though there are of course plenty of novels categorized as fantasy with incidental or even more-than-incidental romance.

I do agree that writers can get too caught up/agents and editors can get too caught up in finding work that's similar to what's popular now rather than what'll be popular in the next wave. But I don't think anyone knows what'll be popular in the future -- there may be some reason to believe that, e.g., sci fi/fantasy will increase in market share because I think it may be more popular with younger generations, but it's certainly far from guaranteed.