The class variants are perfectly possible. My doubts are about the classes with special rules after the psionic manifesters, the martial adepts, the vestige pact binders and the incarnum soulmelds. If the totemist shaman class comes back, it will be totally remake. Maybe the incarnum will work as metamagic feat effects or adding monster traits, so simple DMs will can use monster with incarnum soulmelds in fast fights. The vestige pact magic will work like a temporal mini-advanced class or a monster template. Maybe we will see a Kara-Tur with martial adept classes using martial maneuvers like the ones from "Tome of Battle: Book of Nine Swords".
* The next edition will be a spin-off, a board game with simpler rules for +10y children, and with the option of solo games with a mobile app as AI (for monsters and hidden traps+secret doors). I suggest the name "Endless Quest" as a spiritual succesor of the famour Hero-Quest dungeon-crawnling tabletop game.
* The challenge for the d20 system is you can create a d20 Conan and a d20 Salomon Kane, but they can't face each other without troubles for the power balance.
* I am thinking about other of my crazy ideas. A D&D version of my little pony but with centauresses, and theses have got different morphologies. A cute face with equine traits, like horse-girls from
furry fandom ( = antropmorphic animals) cartoons, with big nose holes to aspire more air for great physical efforts, like races), and the ears on the side like humans, monkeys and apes, not like horses, and below the baist wouldn't be like the classic centaurs, but more like four-legged humanoids. The lower limbes would have got fingers, one of them a true hooeve, and two of them opposible, allowing to be no-so-bad climbers. The lumbar vertebrae wouldn't be too long, allowing to brush their hairy tails with their ownn hands (upper arms are longer than usual body proportions for humanoids). Only one rig cage (proportionally bigger than the rest of humanois) with a mixture of shoulder blade and pelvic girdle for the limbs in the midle), and two lungs and one heart. The body proportions would be more like the fuko figure of Orisha, the centaur-like robot from Overwatch.