Not being able to provide the one thing they/we all will need: custodial care assistance. Many are spry through their nineties, most are not and become slaves to the options of give up your home and move into the pre-death factories, folks believe are nursing homes. In my area, it does not seem that elders are honored and cared for as they are in other cultures. When people have no/limited resources, options, guidance or support, it is so painful to see the final struggles just to live with dignity.
Mobility, communication, and nutrition/hydration
The only challenge faced at my level is not being paid well enough.