If I were going to make an actual real suggestion instead of the typical snarky comment I usually do, I think there is a market that (to my knowledge) is relatively untapped - at least by the major producers of the game. And that market would have crossover with new players, busy adults, and casual gamers. It's something I frequently complain about on here in the way WotC produces their adventures.
I'd like a product line with well-organized, shorter adventures with easy-to-parse details and streamlined encounters. Something akin to what Necrotic Gnome does with their OSE adventures. Compared to those, the adventures WotC makes are stuck with the design and layout of the early 2000s - huge blocks of text, mountains of read-aloud text, incessant page-flipping to get to stats you need.
There was a push in the end of 3.5 to break-up the format of official adventures (I remember Ravenloft was done this way) and in 4e to break into "encounter zones" and include stats in the relevant sections.
If a DM buys your product, it should save them time. You shouldn't have to spend nearly as much time prepping the purchased adventure as you would writing your own.