There is no doubt that moving to higher strength steel , carbon fiber type composites , aluminum , etc can help shed weight, but odds are they will add to the overall cost of manufacturing the vehicles. Will people be willing to pay more? Time will tell.
i work for a company that tests automotive components and entire vehicles for all the manufacturers, and we were just commenting the other day just how much a simple control arm has changed over the years.
In the OLD days, they "seemed" to be stamped out of 1/4" plate steel and weighed a ton. Nowadays with all the solid modeling tools they have, the same control arm has morphed into a sleek hollow aluminum casting with much more strength, and only a fraction of the weight.
We have come a long way over the years.