What is the meaning of "Ki Yimle'u"?
Radak #1: This is not a Brachah. Rather, when your days will be completed, and you will die
Bamidbar Rabah 14:12: Hashem told David that he will live all the years allotted for him. Adam was supposed to live 1000 years. He gave 70 of them to David. Yefe To'ar (Bereishis 58:1) - he will finish his last year (die on his birthday, like it says about Moshe "Me'ah v'Esrim Shanah Anochi ha'Yom" (Devarim 31:2. According to Shabbos 30b, David did not know this. Hashem told him only that he will die on Shabbos, and every Shabbos, David would learn Torah the entire day so the Satan could not take him. - PF
Why did He say "you will lie with your fathers"?
Malbim: You will not die in war.
Why did He say "I will establish your seed after you"?
Malbim: He will not rule over you in your lifetime, like Avshalom attempted. 1
Even though Shlomo was anointed in David's lifetime, and he reigned in David's life (this is almost explicit in Melachim I, 1:39-53, and so wrote Malbim (I, 1:35)), he did not rule over David, rather, with his permission. (PF)
Why did He say "Asher Yetzei mi'Me'echa"?
Radak: This shows that it will be someone not born yet, and not Avshalom or Adoniyahu. Malbim - This is like it says in Divrei ha'Yamim I, 22:9 "Hinei Ven Nolad Lecha
Radak: David did not yet know who it will be, until Nasan called Shlomo "Yedidyah" (12:25). Or, Nasan explicitly told David. Even though it is not recorded in his words here or in Divrei ha'Yamim, we find that David told Shlomo (Divrei ha'Yamim I, 22:8-10) "Alai Devar Hashem
