Is 4.7.x end-of-life? Why does my site say that 4.7 has reached the end-of-life?
There is a helpful explanation.  The numbering system changed, this is detailed here

5.0.0 is the next version after 4.7.31 and is not a major update.   

In The Q&amp;A section there is an answer to this question which explains why the limitations of the update messaging system in 4.7 led to the decision to use the End of Life message in this instance:


  The in-app messaging in 4.7.x was hard-coded several years ago. For a site running the last 4.7.31, we can only display one of two messages -- either that 4.7.31 is up-to-date or that it 4.7 is end-of-life. Neither message is accurate or desireable -- the truth is that 4.7.x was renamed to 5.x.
  
  We've updated the notification system so that future messages can be
  more nuanced/accurate, but for sites currently 4.7 we've had to take
  an awkward approach. For April and May, we used the understated
  message; but in June, we switched to the overstated message.