Personally, I hope they don't do this. Or if they do, they don't do it like they did with 2e.
In 2e, they felt it was somehow necessary to explain exactly what each race was and how they fit into *every* campaign setting WotC put out, thus furthering the integration between the settings that was, IMO, a major PITA.
The problem is, of course, that what is an elf in one setting isn't (nor should it be) an elf in another setting. In your setting you might have kinder-like halfings. In mine, I might have hobbit-like halflings. In some settigns, elves are shorter than humans on average, in others they're lanky and uber-tall.
If there were some way to write a race book that either acknowledged these differences, simply didn't address the physical and cultural side of the races, or said flat-out that the descriptions were campaign specific (Greyhawke only), then I suppose they could do the race books.
