It's a good interview and worth listening to. But you can start at the 13 minute mark for the specific information, and in particularly at 14.30 he gets to talking about not doing two full campaign books a year. Picks up again at 17 minute briefly as well.
I'll probably listen to the whole thing, but wanted to get to the interesting discussion. For context so I could reply here.
It does sound like they may not being doing the 1-10+ adventures. That means they might be going to 10-20 for a couple, or a bunch of modular adventures (like
Dungeon Delves) or other products like a campaign setting or splatbooks...
For the sake of the Adventurer's League and the established audience that runs the storylines, they need one big level 1-15 adventure each year. But the spring product can get more experimental. Like a bunch of unconnected dungeons.
It makes sense. Not everyone gets through a storyline every six months. They can take a good year. And as new players come in, they have more of a back catalogue. So new ones aren't competing with other RPGs but with everything published prior.
(I've mused on this with Pathfinder, which has far more APs yet most people have only played a half-dozen.)
The gaming business is tricky, as you don't need perpetual releases of anything. You need a book of classes, a book of magic items, a book of races, maybe a couple monster books, etc. It's not perpetual, and after a while you're better off just stopping. A finite number of books.