This reminds me of the 1974 World Atlas of Golf, where the forward was written by Alister Cooke (?) who said golf would be outlawed, dead, and only practiced by very secret societies. This was an (over) reaction to the US reducing tax writeoffs for country clubs the year before. When I went in to interview at Killian and Nugent a few years later, I commented on this, and Dick Nugent said....."Golf has been going strong for 500 years and survived worse than a reduced tax write off......it will continue."
Charlie is right in my experience that in any hobby or pastime, most in it feel the kids aren't doing it, it is on the slow death spiral, etc. Yes, some pastimes will dwindle and new ones will replace them to a degree. I don't think golf will look significantly different in 30 years, but the changes will come around the edges, i.e., less green, perhaps take out back tees at most courses no one ever uses, less formality, continued improvements in convenience (carts, shorter courses, etc.) People are logical and golf is a tough biz, so it will shake itself out in a way that allows golf to thrive.