I *think* that *probably* what happens is that you put in a raised shower now, which your wife deals with quite nicely for the time being. If your wife's condition deteriorates, SS sends someone round to add some grab handles at different places in the house, so she can manage a bit longer.
Eventually, you re-evaluate the position entirely, and someone (possibly SS) installs a wet room on the ground floor.
Sorry to depress you. :(