Every year I occasionally check up on how the patent pool is holding up for both CDs and DVDs, like my personal spin on Public Domain Day.
Some good news: enough CD and DVD patents have lapsed that now all of Hitachi's (now HGST?) DVD-ROM patents have expired. The same happened to DVD-Audio last year. Much like CDs and cassettes, I don't see DVDs immediately vanishing just because Blu-Ray discs already have a much larger capacity overall. Plus a *new* factory just for manufacturing more ferrofluid in ~2018 was partially because of cassette demand growing.
I may as well list out what *hasn't* expired by the longest patents in each category, because some have had less corporate priority than others *cough* DVD-RW *cough*.
8. DVD Video Recorder - JVC/Kenwood, 2029-01-06
9. DVD-R Drives - JVC/Kenwood, 2027-12-13
9. DVD-RW Drives - JVC/Kenwood, 2029-01-06
10. DVD-R Encoding - JVC/Kenwood, 2027-12-13
11. DVD-R Disc - JVC/Kenwood, 2027-12-13
12. DVD-RW Disc - JVC/Kenwood, 2029-01-06
Basically paruse
https://www.dvd6cla.com/list.html and look at the older patents. I say this because I seriously doubt that the patents listed above contain the silver bullet to cure all of the format's real flaws.
Also going to point out that pic related is the last stated MPEG-4/AVC Attachment 1 patent in the VIA-LA (formerly MPEG-LA) patent pool to expire, which may technically mean that MPEG-2 will have a longer patent regime thanks to Malaysia granting 2 patents around 2020 (MY 163465-A, MY 177139-A). All of this information is very loosely gathered together, more for a core point: this stuff is expiring sooner than people realize because time doesn't stand still.