I’d guess this is coming about the time these things start hitting the used car lots. Who in their right mind would want one of these things if it needs a battery, & that is a possibility if it has any miles(or years) on it. Maybe somebody could develop an ICE conversion for one of the EVs. That would be a switch and an expensive one too.
The switch from EV to ICE will cost double or triple of a new ICE car. The car structures are radically different to support batteries which are not in same location as the ICE engine. GM’s new design positions batteries over a large rectangular shape under the passenger compartment.