Conventional artillery produces tiny fragments, think steel toothpicks, they'll shread unarmored vehicles, infantry, and even armored vehicles if they're close enough to the blast, as the fragments are still moving at a higher velocity. Anything armored that can take a 20mm can shrug off anything but a very near Miss or direct hit. Nice compared to the 150meter radius kill zone for a modern 155mm frag shell.
What will probably happen is a change in shell design to incorporate larger fragments, or purpose built projectiles, tungsten balls/flechettes. It will lower the killzone but increase armor lethality.