The new policy simply requires that you own, and continue to own, either any points purchased before April 4, 2016, or, alternatively, any points purchased from DVD after. The perks affected do not depend on actual usage or number of points you own like the restriction on the Disney Collections, created in March 2011, does.
Thus,
absent further rule changes, and I emphasize that because who knows what Darth Vader (alias Ken Potrock) will do next, you could sell everything you owned pre-April 4 except a 25 point contract and keep the perks, even if you buy resale after April 4. Moreover, a new purchaser could purchase resale today and then buy a 25 point add-on from DVD and get the perks. However, you cannot sell everything you owned pre-April 4 and then buy a resale and use the perks.
Additionally, use of the perks affected by the new restrictions (other than the Disney Collections restrictions created in 2011), such as for merchandise, restaurant and AP discounts, does not depend on actual use of the points for any trip, and thus you can use the perks even if staying off-site as long as you have the minimum 25 point ownership required.
As far as the Disney systems keeping track, it will take only an adjustment to the existing system which, to enforce the Disney Collections restriction, already tracks resale points and those purchased from Disney and when you purchased them. Also, it appears DVD is going to have different
DVC member cards, digital or otherwise, that will be issued to those who own only resale points purchased after April 4. There will be some oppurtunity for existing DVC members to be able to sell everything they owned before April 4 and improperly use some of the perks until the new membership card now being issued to pre-April 4 members expires, unless Disney adopts computer systems that check whether you are actually a DVC owner when you try to use a merchandise or restaurant discount.