Consumer demand will surely shape the future health care system for seniors, but perhaps not as much as consumer demand affects other markets. The system will also be strongly affected by what the government and/or insurance companies can afford.
In a market economy, all markets are affected by consumer demand. We can already see to some degree how this has been the case in the health care system. There is more demand for various kinds of tests and anti-aging procedures than there once was. We should expect to see more of that. We might expect to see more demand for assisted living facilities. In short, since there are going to be so many seniors with the aging of the baby boom, we will see a much greater demand for various types of care that seniors want and need.
But this will not be the only factor to affect the health care system. This is because seniors will not generally be paying directly for their care. Therefore, their wants and needs will be mediated through government programs like Medicare or through insurance companies. Those entities are going to want to keep the cost of care down. This will also shape the health care system because it will create boundaries and limits on the kind of care that most seniors will be able to get.