End stage Alzheimer's; how long does she have?

IDK Margaret, I am very hesitant to make such predictions because even though my mother is stable now the slide from relatively healthy to invalid was sudden and steep, followed slowly by recovery and plateau. Liljewey18 also mentions her MIL being "unable to stand", in end stage ALZ that ability would have usually already been lost.

Liljewey18, has she been checked for a UTI?

If she is deteriorating fairly quickly (not stabilised like cwillie's mother), probably not long. My crystal ball says 2 weeks, but then I've never trusted it myself. If she is choking on food, I hope that a feeding tube isn't going to be forced on her. For your husband's sake, reality is that the sooner the end comes, the better for her and the rest of you. Then you will all be at rest.

Is she on hospice or in a facility? The pros there can give you a better guess than any of us here since we don't really know your MIL. I can tell you that my 99 year old mother, who has Vascular dementia, has been existing at that level for years. I do know that once people refuse 'all' food and drink they usually don't last long, but people can go on a very long time with even a very small intake.