At any point if there is pain. Then the question will be what kind of medication to use to relieve that pain. No one can predict how long it can be or how much time it will take. Some people fight and fight and stay around and others go very quickly. It also depends on what is the issue and what medications are being given. I know it is a very tough subject to approach especially with other family members. It would be nice for everyone to get together and be able to make their peace and say their good byes before it is too late but sometimes that is hard to do for some. Death is not easy for anybody. Just make sure that the patient has pain control of some sort and hope and pray for a peaceful passing. There are many signs and things that can be expected near the end of death. That might seem hard to deal with but its part of the process.
Please just encourage family to be with her and know that it is not your responsibility to get everybody together. It is up to each individual whether they will be present or not. You can however encourage your husband to be there every step of the way.
Hope that the family can come together and be there for her in this time of transition.