DG has most often been compared to skateboarding as it pertains to its rise and its mainstreaming. Now, I'm not a skateboarding expert, but it seems like the equipment is probably comparably priced to what it used to be and there are still quite a number of free skate parks on public lands. There are probably also a number pay to skate parks, but those haven't replaced the free places, just added to them.
We will NEVER get to the point of ball golf, which is what I think you are afraid of. Ball golf was adopted by the aristocracy at a very early age. The wonderful part of the aristocracy is their utter unwillingness to change. Our game won't be co-opted by them and will always be a game of the common man. Any implication otherwise is lunacy.
Yes, I may be reaching a bit. But keep in mind that a skate park takes up a fraction of the real estate and requires a fraction of the maintenance of disc golf. That said, if all it does is reach skateboarding popularity, I suppose it won't be so bad.