Good questions, Lisa!
For me, the obvious first step in creating collective change involves awareness. Nothing changes unless people identify a need for change and make the argument(s) for it in public spaces where others can listen, refine or expand the arguments, and discuss ways to move forward. Speak up! Speak out! Join in!
In many instances, the market itself will spark a radical design innovation. If many people can't use or don't like your product, social media will gear up its complaint network. Your product won't sell, and your young engineers will be forced back to their drawing boards, perhaps remembering to test their new models on the disgruntled populations.
I plan to write more about the need for design changes throughout our social/economic/political fabric, not only to accomodate our aging population, but also to address problems in broad arenas such as professional healthcare, the food system, environmental conservation, workplace flexibility, and teaching/learning.