Rashi: Like the breach of a wall that fell. Radak - after the building falls, it is a breach. A breach does not fall! It is called a breach, for in the end it will be a breach. The same applies to "va'Tachani Kamach" (47:2).

Malbim: If a wall lacks a strong foundation, when its foundation softens and begins to sink on one side, until it cleaves in its middle. Then the stronger the building, it is more prone to fall and break. A wood building does not break so quickly, and its fall is not so great. Peretz Nofel describes this building; it is the breach that appears in a strong wall.

Rashi: It is exposed, to enter in the walls of your strongholds. Niv'eh is an expression of exposure, like "Niv'u Matzpunav" (Ovadyah 1:6). The Targum is Isgalyan Matmerohi.

Rashi citing Dunash: Niv'eh is a protrusion. The wall became like bubbles due to the rain, and rickety because the mud was ruined. Radak - it says that the wall is tall, for it weighs down on the bubble in the middle or below, and it can fall suddenly. Similarly, your sin of asking Egypt for help will cause a great fall to you that cannot be healed, like that of a tall wall. Its rocks break, because they were banged greatly [against the ground] due to its height. Pharaoh is compared to a tall wall, for they considered him like a strong wall to protect from the enemy.

Malbim: They cannot make preparations to save it.