Such a pack would shave 500 lbs off my Bolt, putting it in Honda Civic weight territory. For a 2,800 lb 215 kWh Silverado battery this tech could cut over 1000 lbs easily. The main issue is economics of it, but a weight fee adds economic incentive to lighten cars/trucks to spur this on.
Researchers have made cells that are over 700 wh/kg in a lab, so there's a possibility of saving even more weight years down the road. The holy grail is a structural battery, so the frame of the car itself is a battery. That basically adds zero weight, though repairs after a crash might be insane.