Reading the Book of Estate, I noticed the rule to stop rolling for child survival after 8 years was removed (15 years in the KAP rulebook). Is this correct? Now, children have to roll until they die (either from misfortune or old age)?

Yes, it is correct. The total death toll is about 30% until 21, so you'll get 70% survivors, which is much better than the KAP 5.1's about 20% survivors (Quick fix: lower the death chance in 5.1 to a roll of 1 and abolish the Standard of Living boni for Child Survival -> about 45% survival rate, which is already much better).

Now, if rolling for every year is too much of a hassle, here is an easy house-rule to use:
1. Roll 1d20: on 5 or less, the child dies during childhood (i.e. before the squiring age).
2. Roll 1d20: On 14 or less, this is the age when the child dies. On 15+, the child dies during the first year.

It gets close enough and unless you have a significant yearly changes in the survival chance (higher Standard of Living or some other things), it is pretty accurate. The advantage of using something like that is that you can roll the survival as soon as the kid is born, and then don't have to bother with the yearly rolls until s/he is old enough to be interesting (find a squiring position or start thinking about marrying the daughter off to someone).

Not contesting. In fact, I understand why it was done. I was just checking my eyes weren't deceiving me.

(Quick fix: lower the death chance in 5.1 to a roll of 1 and abolish the Standard of Living boni for Child Survival -> about 45% survival rate, which is already much better)


Even better quick fix is to drop the death chance to 5% and then stop rolling after 7 years of age. This gives the 70% death chance that it is in BotE.

And no, your eyes were not deceiving you. :) It is just that when we were calculating what the death chance should be, there was no particular reason why we shouldn't roll for every year regardless of age.