It's an intersting time to live, we are indeed seeing the peak of ICE, though I think there are lots of room for improvement in EGR, compression, more efficient catalytic process.

"smaller market" ICE manufacturers IE isuzu, mazda, hino etc. are sort of working towards this, as opposed to jumping on EV train.

Theoretically, it's completely reasonable for a high compression inlne 3 cylinder with aero wheels/tires to get 60-70 MPG. (With proper EGR, turbo application, CVT)