So you'll need to estimate changes to both income and expenses. You will spend less on some things. After all, if you're not working you won't need work clothes. Lunches at home are cheaper than lunches out. And it might be possible to get rid of that second car.
Every case is different.
But, new expenses can more than eat up any savings. While some disabled persons are able to care for themselves, others require in-home nursing care or even a move to a nursing home. The healthy partner, if there is one, could be too busy working to complete all the household chores so non-medical help could be required, too. Because no one knows exactly what the future will hold it's hard to decide whether you need additional disability insurance and, if so, how much is appropriate. The best you can do is to think of some things that could happen and think about how you'd react to them.