The kid should have been arrested for hit-n-run.
As for the Malibu, it probably will be totalled. Just in the pics I see damge to the enitre door portal, not just the B-pillar. There is definite damage to the sill and rockers around the pillar, and the arch right at the B-pillar. The suspension mounts at the right rear are probably badly damaged, and the under body probably has some minor damage, things like brake- and fuel- lines and exhaust may also have been damaged. Just the fact that the Bu got hit hard enough to spring the fuel door open is a bad sign...