Presumably, Netflix will in the short-term pay X amount for this but work probably started yesterday or earlier to replace it with something that doesn't have fees to use.
[1] https://research.netflix.com/publication/AV1%20at%20Netflix
For netflix? its not that simple. Video codec design is a mammoth task. Sure you can make your own fairly easily, but making an efficient, hardware accelerated encoder that is suitable for broadcast work is one thing.
Making a spec for consumer hardware to implement, efficiently and cheaply is another.
go and read the spec for MPEG2, then compare it to MPEG 4, with all the amendments to make h.264. Its a lot of work.