The usual view is that, while overall there will be more water vapor (already increased by some 7%), there will also be areas that will get drier, especially many places already dry now, and interiors of large continents. Also, as climate zones move poleward, arid regions will move (are already moving) poleward, so in the Northern Hemisphere, places now north of major deserts are likely to become drier.
Yes, ag, overgrazing can make things much worse, but there have always been areas that were drier and areas that were wetter, and the dry areas tend to fall at certain latitudes because of Hadley Cell behavior, which others who know more about such things can certainly elucidate much more clearly than I can.