Rashi: The kings that we had before Pekach, e.g. Yeho'achaz ben Yehu, that in his days they were diminished "Ki Ivdam Melech Aram" (Melachim II, 13:7). They were lowly, and passed like a fragile building of bricks. What is now is strong, like a building of cut rocks. Malbim - i.e. we need not fear due to Retzin's fall to Melech Ashur. We will choose helpers stronger than Aram!

Targum Yonasan: The first were exiled. Radak - this is a metaphor.

Mahari Kara: If Pekach, who was weak, died, we will make Hoshe'a ben Elah king in place of him; he is strong.

Rashi: If sycamores were cut, we will replace them with cedars, which are better for building. Metzudas Tziyon - this is like a repetition of "Levenim Naflu v'Gazis Nivneh."

Malbim: If a building of bricks fell, one can rebuild it stronger from cut rocks, but he is pained by the expense. We are not pained at all due to Retzin's fall. Rather, we are like one who has a forest of sycamores, which are inferior. The owner himself cuts them in order to plant cedars in place of them. He is happy if others cut his sycamores! So we will rejoice over the fall of Retzin, who was a weak help; in place of him we will make a Bris with cedars and Giborim. The first metaphor (Levenim Naflu?) corresponds to Ga'avah; the latter (Shikmim?) corresponds to Godel Levav (8); they think that it is for their benefit.