https://www.theregister.com/2023/09/26/ ... port_2023/
They have come to the conclusion that there's really no point in maintaining them that long, because people are not using them. So the six-year update policy is going away. When 4.14 goes out of support… early next year… there will not be another six-year kernel to replace it. We're likely to go back to a long-term stable kernel maintained for about two years. After that, people will simply be expected to update to a newer kernel.
The new regime
When 4.19 reaches its end of life, so will 5.4, leaving the end-of-2020 kernel 5.10 the oldest longterm release. This change was discussed at the time, but now it looks like what is essentially the worst-case outcome has been chosen.