This seems unlikely given that the Volt has been canceled and much of the momentum is moving towards electric only platforms, even from the major manufacturers.
Sedan marketplace is shrinking, SUVs are growing. GM doesn't want to waste its hybrid technology, but also doesn't want to bet on the Sedan market anymore.
EDIT: Note that a 20-mile range PHEV (the typical one) is insufficient. 50-mile range PHEV seem to be the sweet spot for me.