Nice Pic
I believe Boeing have a replacement for the 737 on the design board 797??
It may not be a quantam leap like the "Comet/Caravelle" but if the items you list are fuel saving I am sure Mr Boeing will be looking at it indeed
The engines could be e.g. Geared Turbo fans, optimized for low noise and a relative low but fuel efficient cruise speed. The configuartion is further optimized for low noise (tail / wing deflection), low drag (5 abreast cross section) lean wings, and focusses on regional / feeder / low cost (6 abreast) markets..
But I suspect it will be a carbon/plastic aircraft similar to current shapes with a new Gen engines and not very interesting to look at unlike your artists impression pic.
