I understand that there is a difference between alzheimers and dementia, but I believe many of the differences are usually small.
My Mother passed away in January of this year - from Dementia. She was officially diagnosed with dementia about 3-years ago while in the hospital after falling down. Undoubtedly, it began much earlier.
She was, for 15-months, back into her own home but with a doctor required 24/7 caregiver. Then, her last 16-months were in an Assisted Living for Dementia and Parkinsons - a terrific specialized Home. And that was a requirement by the hospital psychiatrist after one of her major evening hallucinations put her into the hospital.
I feel for your partial family to have to deal with all the forms of support for your father-in-law. It isn't fair .... and it IS harder on the supporting people than on the patient - at least in my belief!!!
In my Mothers case, she had money put away, so that it was not a financial burden on me - although by the end, her money was close to running out. For moral support, it was just me .... and at times, one of my daughters. But the other daughter washed her hands and continues to wash her hands of helping anyone - unless there's something in it for her.
Toward the end, many of the reactions of my Mother were very similar to what you're saying about your FIL. The staff, at one point in late 2013, suggested that I bring in hospice for her.
That organization was terrific. They were caring. They did not get into the way of either the Assisted Living staff or the primary doctor. They kept me informed - as often as I wished. And the purpose was to make her final days as pleasant and pain-free as possible.
The hospice was paid for by medicare. The duration of hospice can be almost anything. In my Mothers case, it was close to three months. It can be much longer though often is not.
I don't know that anyone could tell you if your FIL is nearing the end. I think it's safe to say he is in the later stages though. In my Mothers case, the AL staff was very careful NOT to give any kind of timeframe for her. But, when hospice is suggested - it's getting close.
Hospice called me three times the day my Mother passed - to keep me informed - and to let me know that her time was very close. Swallowing food does often become very difficult. It was for her - and that often leads to difficult breathing and/or pneumonia at the end.
I wish you and yours peace.
Rob & Gizmo