How much longer?

You mean that there are friends and relatives who want to "say goodbye" but have no interest in visiting until the very end? You owe these people nothing. Say, "She is still alive now, and would love a visit from you." If and when they decide to visit is their business. You can only tell them what you know, which is there is no way to predict when the end will be.

Hospice is not being evasive. They also don't know.

Your situation has too much inherent stress to add the needless stress of satisfying outsiders' curiosity.

Consider posting updates on a site like Caring Bridge, so everyone knows what you know. That is the best you can do.

My MIL has CHF. You will see the BP and HR become unstable. You will see fluids build up in the legs. Then the fluids move into the abdomen. Finally they get to the lungs. You see coughing. With a stethoscope you hear the lungs muffled, crackly. The patient is short of breath. They become confused, they complain of cold hands and feet. GFR drops, that's kidney function. Liver enzymes go up as the liver fails. There are good days and bad days, but the rule of thumb is that if you see decline over months, there are months to live. If they decline over days, there are days to live. At the end they will decline over hours, with just hours left to live. My father had months to go when he suddenly died of a stroke. My MIL on the other hand, seems to be cruising smoothly and hospice is not in the picture yet.

It's hard because you love her and don't want her to die, but you're tired and trapped, and you do want her to die, and people keep asking you the question, and you think you would feel better if you knew......

If you have any faith, this is one problem to turn over to God. You cannot predict or control it. For thirty seconds at a time, accept your powerlessness with serenity. Then do it again. It can become a habit, and it can give you some peace. It is really hard, I know. Bless you.