A few days ago I purchased the DVC after a short and not very informative presentation. After getting home I started to do my homework on the net and find that finding places to go by RCI are nearly impossible to secure.
Depends on the location, time of year, resort sought, etc. I think it's a mischaracterization to say that RCI destinations are "nearly impossible to secure." But it's a situation where you really need to research how trades work in order to maximize your odds for success.
Right now...in October...you probably won't get a Colorado ski week for this winter or a prime beach destination for Spring Break '15. But those who planned further in advance have had success.
All of that said, I wholeheartedly agree with the others that there are cheaper / more effective ways to vacation than using DVC to trade worldwide. The point banking and borrowing provisions mean that DVC ownership can still "work" even if you only use the points once ever 2-3 years. In that situation, buy fewer points and combine 2-3 years worth for one trip.
IMO, if you are planning to trade through RCI any more than 10-15% of the time, I think you need to reevaluate your approach.
Something I should have added is another reason for buying was children and grandkids. They seemed somewhat pleased about it but we also don't want to burden them with forced vacations at one venue.
Would it be a good thing to hold on to for the future even though it's not predictable?
Well, I wouldn't buy unless you have very specific use in mind. DVC is an expensive purchase. It makes no sense to buy with the mindset of "at least we have it whenever we want to go to Disney."
Even using points for the DVC resorts requires advance planning. All owners have a 4-month booking advantage to secure a room at the resort they own. But taking advantage of that feature requires planning more than 8 months out. From my experience, owners who cannot schedule their visits more than 8 months in advance tend to be disappointed.
As for the impact on children/grandchildren, depends on their personal mindset. There are many people who would be thrilled with annual visits to Walt Disney World. Others...not so much.
At the presentation most of the hard questions I asked were answered with " Trust the Mouse " or Dis doesn't wouldn't that. Hmmmmmm.
Depends entirely on what you asked.
The DVC program has been around for nearly 25 years now so obviously there is some track record with regard to their decision making.
The legally binding documents are vague enough in many areas to allow Disney to maneuver. It's similar to the impact that your local government / homeowner's association / employer could have on other areas of your life.
Any decision Disney makes impacts not only current owners but their ongoing ability to market Disney Vacation Club to new buyers. At the end of the day, every current & prospective owner must reconcile what COULD happen with what they really believe MAY happen.
Bill 
