Ah, but Ouran probably would have sold with or without a dub because it has psychotically devoted fanbase. They were starved for that show.
Where a dub is truely questionable are shows where the fanbase is more fairweather and/or just extremely small. Like, not a lot of people are say, itching for Kodomo no Jikan or Strike Witches to hit the states, and the fact is a lot of the people who would look for those shows could probably care less about a dub and probably would opt for a preorder bonus upsell like figurine or poster or something.
Honestly, what the industry now neeRAB is a more exact approach. Some titles can be dubbed and maybe even in single volumes. Others are gonna be boxsetted from the get go and be sub only. All in all, that precision will be a good thing. Less waste, better marketing, shorter overall turn around times.