I think of reverse mortgage more as a final safety. Something to cover elevated end of life expenses. A nursing home for instance. At that point, it doesn't matter quite as much if you wipe out equity and frankly at that point most people aren't alive long enough for the interest to gobble up their equity value.
I don't think it's smart to do that now. I know the rules are that she can't be forced out of the house but over the next 20 years it seems possible she could end up with next to no equity.
You would really need to get more specifics to figure out the answer.
Doesn't work for nursing home costs since once the home is no longer your primary residence it's supposed to be sold. If both members of the couple are on the house and the reverse mortgage it would work on the first to go into a nursing home if the second partner remains in the house.
What Catbert is referencing, is the asset spend down required for Medicaid to start paying nursing home expenses. Nursing home care it so expensive, and medicare covers so little, that most people who end up requiring nursing home care in the US need to qualify for Medicaid at some point. One of the points made
here is that the monthly payment from a reverse mortgage would put you over the asset requirement for Medicaid. If the house is sold, it seems the reverse mortgage is paid off and the payments stop. So if the reverse mortgage payments aren't enough to cover the nursing home, and you're out of other assets, you'll need to sell the house to qualify for Medicaid.
But I think it's an even worse idea for the healthy spouse to get a reverse mortgage to pay for the sick spouse's nursing home stay:
1) I doubt the reverse mortgage's payments are enough to cover a nursing home stay
2) The healthy spouse is allowed to keep the house (no matter its value) along with some income, while the nursing-home spouse qualifies for Medicaid.
Instead I favor accessing the equity in your house sometime in your 70's when you can use it to enhance your life, or make sure you can pay your property taxes, insurance and other expenses. I'm thinking here of my neighbor who mowed is own yard, lived with an old truck, heat his house with wood, and didn't seem to go many places. He could have lived better with a reverse mortgage, but he didn't (I think). In the end, his estate ended up with the same amount of home equity as if he would have funds from a reverse mortgage, as he ended up in a nursing home and his kids helped sell his house with all the proceeds paid to the nursing home in order to qualify for Medicaid.
** I should add here, that I've only ever thought about reverse mortgages that are the "Tenure Reverse Mortgage Payment" type. These make payments over the borrowers' life, like an annuity. There are other payment options, many of them quite scary:
https://www.investopedia.com/mortgage/reverse-mortgage/how-avoid-outliving-your-reverse-mortgage/