Patrick,
great question.
from a societal perspective, i think that reclaiming storm and greywater would become essential in urban areas... if you ever look at the volume of water used in things like your kitchen sink, and laundry, you'd be amazed.
of course, regulatory processes will have to loosen (more) to allow this water to be treated, and put back into the hydrologic system for landscape, and even some household uses (ie/toilets).
Golf wise: it would be possible for the game to survive, but i think there would be a greater emphasis on using greenspace/green infrastructure including as golf courses, to treat local grey and storm water... some of that water could then be put towards irrigation.
as far as Ian's comment goes "golf will be for the very rich"... i think thats true.. but only partly. in some maybe perverted ways, i see an increase in water cost as a good thing, in terms of altering expectations of the "average" golfer - ie/ the north american golfer accepting the aesthetics and realities of a course that looks like Hoylake last week, rather than the lush, soft, green they've been acustomed to. The "very rich" would still be able to have their lush green fairways, but they would be the exception, rather than the rule.