Correct about physical books, and I doubt physical books are going away. However, WotC has been leaning towards digital distribution, and hired on people with experience in software-as-a-service.

By all means, keep playing the version of the game you own! But it looks like the future of D&D might make a lot of content available to rent, not to own. Hopefully I’m wrong, but honestly, there are plenty of other games that let you own your stuff.