Why does it say "Ki"?
Radak: The Temimim will not be ashamed, because the Resha'im will perish.
Malbim: This is for contrast. Hashem fulfills the days of Temimim and the inheritance is forever (verse 18), but Resha'im will perish and not complete their days, and their inheritance will not remain. Also refer to 37:20:2:4.
What is "ki'Ykar Karim"?
Rashi #1: Like the light of a morning cloud that whitens the plain; it does not last. "Karim" is like "Kar Nirchav" (Yeshayah 30:23); ki'Ykar is like "Ohr Yakros" (Zecharyah 14:6).
Rashi #2: It is like the honor of lambs that are fattened for slaughter.
Radak: It is the most esteemed, best part of the lambs - their Chelev, which is offered on the Mizbe'ach and is Kalah (totally consumed) in fire and becomes smoke. So Hashem's enemies will be finished off!
Malbim: Temimim will not be shamed at times of evil (verse 19), but Hashem's enemies will be like flock fattened on grassy pastures; at a time of hunger, they perish in smoke - "v'Ra'u Kevasim k'Dabram
Why is "Kalu" repeated?
Radak: This is because they will be so utterly finished off. The latter is mi'Le'eil (the penultimate syllable is accented) because it is Sof Pasuk.
