Unless there’s a quantum leap in material science (along the lines of transparent aluminum) airless tires will never come close to the performance of pneumatic tires.
First, compressed air makes an excellent, near ideal spring that’s nearly weightless.
Almost no hysteresis or internal friction, which add to rolling resistance and heat.
Second, all the air in the tire works against the contact patch, whereas with an airless tire only the material (foam, spokes etc.) in the immediate area of the patch is working at any given instant.
Basically about 90% dead weight.