I really don't see them adding anything for pre-50 characters with the expansion. We have enough of that already.

Though they could add a few more low level dungeons I suppose, but they could also easily place those in already existing maps so that they are accessible pre-50.

I expect all new areas and dungeons in those areas to be level 50-60, maybe even have the mob level cap be increased beyond level 60 in some of the areas for added challenge. (Since this is one of the complaints about the game that pops up often. ie. No danger in the overworld)