The runway length is dependent on their expenses. If they earned 100k and spent 50k, it would last 20 years assuming no investment returns. If they spend around 4% of their 10 years salary annually, they're very likely to be fine for 30+ years as long as it's invested reasonably.

https://en.m.wikipedia.org/wiki/Trinity_study

No necessarily. It depends on a person's yearly expenses. If, for example, she was able to save 10 years salery in 20 years, it would mean that she consumes only 5 % of the total savings per year. This sounds quite sustainable, because you need only to achieve a 5 % return on investment (after inflation) on the savings to live just from these returns not touching the savings at all.

Left out my wife is still working and its enough for 70% of living expenses.

Now you follow The Way of the House Husband

If the money is sensibly invested an adjustment in lifestyle might allow you to live on it a considerable time, or even indefinitely.