Remathilis
Legend
But that's the restriction that the game itself puts on them; they are designing for Dungeons & Dragons (TM) not Generic Fantasy Simulator RPG. They are restricted to trying to make each setting still reflect the core game as much as possible; the era of each setting having its own character creation rules died with TSR. Settings should be compatible with the D&D game and assumptions, even when they change or break them.I think that's rather restrictive for the designers if they are required to include every class or every race, or even just the common ones, in every setting they put out. They shouldn't have to do away with a great theme for a setting just to fit every option in the PHB into the setting.
And honestly, I don't see the problem; 3e Ravenloft found places for all race classes and races (though half-orc was refluffed) and 3e Dragonlance found similar space for all the classes and most of the races (again, giving substitute or new races to replace those unavailable). 3e and 4e Dark Sun did the exact same; all the classes are mentioned, and most races are covered (and new races cover the ones that aren't). At this point, there is no official setting that has been printed since 2000 that didn't allow all the 3e phb classes, and the 5e phb only added 1 class and 2 races to that list.
Either way, I expect that when WotC does do another setting, it will use the 3e model and find space for all the PHB classes and most, if not all, races. They may cheat a few in (kender subrace for halfling, calling half-orcs calibans or dragonborn dray) and give more than a few the "these are rare, check with your DM" treatment, but I'm certain that they will be there. It's in WotCs best interests to do so.