First: The OGL and OneD&D:
1) The OGL 1.0c would be implemented. It would be the OGL 1.0a with the addendum "This License is meant to exist in perpetuity, for all time, with no ability to alter or rescind it retained by any company or individual."
2) OneD&D would suddenly look a lot more like A5e.
3) OneD&D would be put under the OGL 1.0c.
4) OneD&D would be placed into Creative Commons at launch.
Then we'd get into the marketing:
1) "D&D is for Everyone" initiative for better access to the game for people with visual and auditory impairment. Braille books, for example. Indexed Audiobooks for quick lookup. Disability peripherals like audible dice-rollers. Fidget dice-replacements like spinners with different internal wheels for different dice-sizes.
2) All books are Print on Demand from DM's Guild. Including Braille editions.
3) Get someone trained in accessibility to streamline DDB with an aim for easy access of materials.
4) Radioplays with young and eager voice actors and writers.
5) Small Scale marketing through actual play groups. Working with Dropout.TV, for example, to subsidize costs for more Dimension 20 material. Do the same for Wil Wheaton to run games with friends and Trek-Family.
6) ACTIVELY SUPPORT THIRD PARTY CREATORS with WotC awards for innovative game design with cash prizes and potential recruitment for new projects.
Then comes Brand Management:
1) New D&D movie focusing in on Practical FX. Sequel set 10-12 years after the first focusing on Doric, Simon, and Kira. (The two who will stay youthful 'til they're around 100 and the kid who is growing up)
2) Shop BG3 engine to various studios to produce additional games in various settings.
3) Kill all "Microtransaction Mobile Games" projects.
4) Open the D&D License to movie and tv studios for movies and shows they ALREADY WANT TO DO but hope to use the D&D Brand on. Work with them to make sure the project is good.
5) Work towards Genre-Busting through settings in various products.
6) Introduce an updated campaign setting every 2 years.
7) Introduce new campaign settings every 4 years.
8) New D&D player-facing material in 2 books per year, one tied to the most recent updated setting, one to the brand new setting.
9) New D&D DM-facing material in 2 books per year, one tied to the most recent updated setting, one to the band new setting, both with a healthy focus on monsters and encounters that can be mined for use.
10) Three Adventure Paths per year. One FR, one tied to the most recent updated setting, one to the brand new setting.
That's 7 new books each year, with an additional book or box set every third year or so. After 10 years that would be 80 books.
20 of those books would be player-facing materials that most tables would buy and probably wind up with multiple copies each year.
20 of those books would be DM-facing materials that most tables would buy and might wind up with multiple copies each year.
30 of those books would be adventures that many tables would buy and most tables would buy at least one of each year.
And then the settings would probably not sell -that well-, but would get die-hard followings either back, or formed.