We already handle seniors and people with mental problems, so it shouldn't be any different. A large number of senior citizens require assistance already, and because Alzheimer's develops late in life, many of these people will already be getting assistance or at least be nearing the time to get assistance.
As things currently stand, I don't think society will be able to handle the flood of Alzheimer's patients, however I think we can change society to make things easier. If we encourage families to take more care of their elderly relatives at home with tax breaks, and are prepared to spend more money on care homes and hospitals for the ill, then there is no reason we won't be able to cope.
Yes, society will be able to handle the coming flood of Alzheimer's patients, because the affordable care act will ration care, so that everyone gets the same amount of care. We will find ways to put them in homes, but the quality of care will likely not be very fair. But all is good under Obamacare. They will grow old with varying levels of care.
If there is a flood of Alzheimer's patients, society will react to the threat.The disease will become more visible and more work will go into treatments and preventative measures against the disease, just as an aging society has handled the diseases of age (heart disease and cancer which affect those in their 40's-60's) so too will it handle the diseases of later years.
I believe that society is quickly adapting to the retiring baby boomer generation and all the medical and health problems like Alzheimer's they are bring with them, I think that society will quickly adapt with treatments and cures for diseases like Alzheimer's and in the end I don't think society will have any difficulty handling the coming flood of Alzheimer's patients.