Productivity may be affected. For those with whom I've worked, elder care is a natural act, one whose lessons are worth the time involved. As you note, many would like more support, both from employers and from their communities. But there is also a need for aging children and their elderly parents to think about and plan for the events that an elder's illness represents.
Employers can help with the information and planning required.
I have heard from many who say it makes all the difference. Perhaps most important, however, we need to realize that this isn't a question of age alone. At present, I'm involved with several families facing chronic and limiting illnesses among people in their 30s or 40s. All are shocked and surprised that they are confronting issues of illness and disability that were, they presumed, attendant only upon age. The issues of your mother's care may in fact apply to your brother's.