Huh. A few things, come to think of it…
OGL 1.0b, a copy of 1.0a with whatever language updates are necessary to make it clearly an irrevocable license. Give ownership of that license to the law firm working on the ORC.
Release SRDs for every edition under both OGL 1.0b and ORC (depending on the terms).
Keep 5E core in print but let the community of 3PP take care of the rest. Slight rules revisions over time to fix broken things more than new editions.
Bring everything ever officially printed for D&D up to snuff re: text, layout, etc, i.e. no more bad scans, aka go back and re-typeset the lot. Sell the PDFs of everything and offer them all up as high quality POD. Yes, many are there already but most are bad scans.
Do Kickstarters every year to do print runs of older core books. One Kickstarter a year but cycle through the editions. Don’t leave any behind. OD&D, AD&D, 2E, 3E, 3.5, and 4E. Basic, B/X, BECMI, and RC. If not enough people are interested, it won’t fund, so no problem.
Open all the settings on DMsGuild. Take less of a cut.
Make “ultimate editions” of all of the settings. Gather up all the lore, all the monsters, all the NPCs, all the locations, all the maps, etc from all the editions. Square any contradictions and publish those. That will be easier for some than others. After the initial release, do Kickstarters every few years to keep them in print. Start with Mystara and Hollow World. Next up Dark Sun. Next is Nentir Vale. Go from there.