Pressure vessel decompression is of little significance in the breakup. There really is no such thing as a hole in the fuselage causing a decompression to finish the job.
With so little damage to the plane that landed the most one would expect is extremely localized damage to the B737. However the real issue is what came first. If the B737 was first ala the breakup of PA103 or TWA800 then it's possible (I have no idea how probable) that small debris might have struck the other plane.
From the pic, the damage to the left wing of the B737 doesn't look like impact damage, but instead more like buckling and overload ala the video of the B777 wing overload test.