I've been an owner for several years and am not sure what the impact on me is.
As an owner there is absolutely no impact on you. Whether you bought your original contract direct or via resale, you will retain access to the Disney Collection, Adventurer Collection and Concierge Collection.
What is under dispute is the impact on resale value should you decide to get ride of some/all of your points. Points sold resale after March 20 will no longer be able to access the Disney, Adv or Concierge collections.
I think it's fair to say that most people believe resale values will fall to some degree after March 20. Some number of buyers will opt to purchase direct rather than resale in order to have access to these options. That reduction in demand for resale contracts should depress prices to a degree. But there are a lot of differing opinions on how much values may drop.
If you continue to use your points until they expire, this change has no direct impact on you whatsoever.