Difficult to answer without “prying” into your parents or in-laws financial situation. Average cost of LTC services is appx. $250/day depending on locale. You have to make assumptions as to “how long” the care will need to be. Typical care options are 1-5 years. If your parents or in-laws have a significant nest egg, they may not even need LTC Insurance. Consider family medical history as well.
There is also “ala-carte” , in-home care services option.
And then the ultimate backup is you and your wife...