Sure, in an EV it's possible to choose not to have that second battery. In an ICE car, it's needed to start the engine. So at least the ICEs are much more likely to settle for 48V than something closer to 60V, to leave room for charging. The manufacturers that make both ICEs and EVs are going to want to share components, so the pure-EV components are likely going to be built for 48V too.
