I spend way to much time here, I kept having to re-translate CJ into Carpe Jugulum instead of chrisjordan
Also, I must admit I personally have little grasp of the way time passes in the Discworld books myself, apart from obvious follow-ups I tend not to think about age and time, and everything may just as well have happened at the same time. But maybe that's just because I didn't really read them in the right order and have missed some out along the way... But still, I notice the growing up of people like Susan or Tiffany, but less so the ageing of other recurring characters, such as Nanny Ogg, Ridcully, Colon & Nobbs...
Others, such as Carrot, Vimes/Sybil, or Magrat don't necessarily age in an obvious way, but their lives are marked but stages, Carrot gets promoted and finds a girlfriend, Vimes and Sybil get married and have a son, Magrat marries Verence, etc. implying that they are progressing through life, but not specifically mentioning age.
And I find this true in real life... until you're 20ish you count every year, and each one is different, you grow and change, time goes slowly enough to notice details, but once you hit what the French call "active life" (I always thought that was underestimating teenagers' energy myself) one year is rather like another, unless something special happens ; meeting/marring significant other, getting a diploma, finding/changing jobs, having kids, etc.
So what now for Esme ? (or Nanny actually ?) Maybe she'll just go out borrowing one day, and not return, still clinging to her "I maybe aten't dead" sign. Maybe he just won't write about her any more, and we'll find out in some later book that she passed away, as you say, once replaced by Tiffany. Or it'll all finish in a grand finale against someone like the Queen, and she'll be the sacrifice so that good can triumph, an' all that... I wonder what she would prefer.
Or maybe she'll finally marry Ridcully (who will of course invite himself to the wedding) and they'll both retire and not have kids somewhere quiet.
I think half the fun is in the "wait and see"
(and don't get me started on Dumbledore

)
Edithed four spulling