- Promptly release OGL 1.0b which includes only two changes: 1) the word "irrevocable", and 2) also say something like: "WOTC perpetually and irrevocably affirms that the previous version of this license, OGL 1.0a, is likewise irrevocable." (Note: I understand that You (WOTC) do not wish to release 6E under OGL1.0a or OGL1.0b. I'm actually okay with that. See further down this post.)
- Promptly re-issue the 3.0 SRD, 3.5 SRD, d20 Modern SRD, and 5.0 SRD with OGL 1.0b documentation.
For me, this is basically all that is absolutely required. (If they did back down to this extent, the PR of it all would also require an apology, but I personally could live without one.) I do think that even this is too much for them.
- As soon as the ORC License is on-line, release those SRDs under ORC as well.
- Announce that the following SRDs will be released soon: an OD&D SRD, a Holmes BASIC SRD, 1E SRD (including 1.5E UA), B/X SRD (Moldvay/Cook BASIC edition), BECMI SRD (Mentzer BASIC edition), Rules Cyclopedia/Wrath of the Immortals SRD (Allston BASIC edition), 2E SRD (including the 2.5E "Players/DMs Option" system, as errata'ed in DRAGON mag), and 4E SRD. Extract the rules content for each of those editions, and release these under both OGL 1.0b and ORC documentation.
These, I'm afraid, are a fantasy. If your OGL 1.0b does come about, I rather expect ORC to fall by the wayside anyway. But even if not, WotC won't want to join.
But adding SRDs for other editions would be a very significant amount of work for no gain - and, indeed, for a loss since the biggest competitor to One D&D will be "older D&D". I would love to see SRDs for these, and especially 4e, but I really can't see it ever happening. Better, instead, to assume the retroclones are the foundations for any ongoing support.