We get this same question a couple of times a week from adult children of a parent who has remarried and the fear is that the stepparent will get everything with nothing left for the bio child.
People who are married often own everything jointly so when one spouse dies the other spouse gets everything, lock stock and barrel.
As for your father's condition now, his wife will be making all the medical decisions if he is incapable of doing so. If they have been married for some time, then it's likely that she already has his medical power of attorney.
When he dies she has no obligation to produce a will. As I wrote earlier, you can open probate under intestate succession in an attempt to force the production of a will. But if all of his assets are joint, it will be a waste of your time and money.