Which is kinda sad, as only the most die-hard fans stuck with the playtest, let alone completed all the surveys. The drop-off of interest in the playtest in my area was dramatic. May have been different other places, of course.
The response rate for surveys is usually pretty low. 50% is usually good. WotC has said the surveys were much, much higher. So there was a range of players.
Through AL. Put out a new setting, with new player materials, run the next season of AL exclusively in that setting with those rules. Of course, they're not really new players, but if a new player stuck around for more than one season...
But what percentage of AL are brand new?
AL is good for new players, but it's also good for players of all amounts of experience. The percentage of new players is likely higher in AL, but a majority are likely somewhat experienced. And players are only "new" for a short period. The people who started playing AL at the start have been playing for a year now, and it will likely be another year before the next non-adventure is released. (And a brand new setting would take a couple years to plan and write, so how many new people would be playing AL in three years?)
That point aside, this doesn't strike me as the best idea.
First, it's changing the rules of AL in mid-campaign. You need to work in world conversions. People will want to continue playing their character, and many will play every other month. There will be a mix of characters.
Second, it's also adding another layer of complexity to getting into the game, adding learning a setting onto learning the rules.
Third, it's hard on the writers. The AL needs to write and plan far in advance, and they'd need to learn a whole new setting, possibly while still in flux. They'd have to throw all their storylines out the window or end them quickly.
AL strikes me as a campaign that needs to exclusively stick to the Realms, regardless of where the storylines are set.
Could be little more than a re-print in the case of settings that don't have all that ongoing-fiction-series change driving them.
But why reprint then when they can just direct people to an already published PDF?
Unless they're doing a full rewrite its easier to just do a 10-30 page campaign conversion document (like the Eberron one), albeit one quickly playtested and revised.
Somehow I don't think someone who wants the officialness of a published setting is going to be too happy with that.
Depends on the alternative. Official is nice if done well. That's the big caveat.
I think most Ravenloft fans were happier with fan conversions than Expedition to Castle Ravenloft. I think a lot of FR fans would have been happier with a fan conversion to the 4e ruleset than what actually happened. Many Ravenloft and Dragonlance fans were pretty darn happy with the licenced 3e products, which were only quasi-official.
Compared to any individual fan.
I'm willing to put time into a fan conversion during my breaks, my lunch, and free moments at work. I'm willing to work on the project during my evenings. On the weekend. I can certainly leverage more hours to a conversion than someone working in a business who needs to attend meetings and give reports.
That's also just on a one-to-one basis. I can coordinate with dozens of fans to edit and give feedback (or add more content) via a Google docs. A dozen fans can output and convert a heck of a lot more information than the three or four writers WotC has on staff.
The D&D community has shown that it likes tradition, which precludes changing the official rules much (as we've seen). But, perhaps paradoxically, what the individual DM /really/ likes is to change the rules. 5e accommodates that. But as we've seen, that encourages homebrewing more than snapping up scads of setting materials. The whole 'setting-sells' thing was a 90s phenom that hasn't come back, as yet (though it certainly could, and D&D'd've missed the boat just like it did the OSR and boardgaming bandwagons).
I'm not entirely sure settings really ever sold that well. They sold well enough for TSR, but they were quite happy fragmenting their audience and competing with themselves and their licenced products. And they almost certainly never sold as well as WotC expected D&D books to sell.