I will note that there's no stability with parking cash in the current environment, but like Robert says: savers are losers, but if you don't have the education to make your money grow, it's better than nothing.

The environment doesn’t currently exist.

This is the type of environment I would love to be a part of.

Furthermore my cousin may prefer to return to her home for the time being, which is a far better and safer environment than a nursing  home right now.The sister-in-law is putting no consideration into arranging a good pay-off figure with the current mortgage lender, nor listing the property on the open market. 

But not married to any location ;)  I agree with Brandon Turner's admonition to live where you want, invest where makes sense.Investing locally -- in addition to the temptation to drive by, sink time -- can come with a cognitive bias of thinking we know more about our environs, including material aspects, than we might.

You may well gain some perspective, but not enough for peace of mind if you're just getting started.

Properties like houses are safer choices because their value won't fall overnight, giving peace of mind.

Our low cost of living, abundant natural resources and business-friendly environment are drawing national and international interests.

The only true pro I see in paying it off is your wife’s peace of mind.Using that money to invest in anything that produces greater than a 3% return is the wise use of the cash.

In a rising-interest rate environment, and at the ridiculously low 30-year fixed interest rate you currently have, I wouldn't attempt to modify anything.