This feels like something only a woman could put forward or demand in a relationship based on their value in the dating market. A man would be in a much higher risk of being left with the same arrangement.
Man here. Before getting serious in my current relationship, I sat down with my girlfriend and gently initiated a frank conversation about about what each of us expect out of a relationship and what our short-term and long-term priorities are, not just in terms of relationship goals, but also in terms of general life goals to see whether or not a relationship would hinder or help those goals. As someone who's experienced, not one, but two traumatic parental divorces in my life, the last thing I want is to get ten years into a relationship before discovering that our goals are incompatible. This isn't anything exclusive to women.
Women and men have roughly the same value overall in the dating market. The guys who say this kind of thing tend to have a narrow view of what kind of woman makes an acceptable relationship partner, and ignore a whole lot of women that are available and aren't nearly as well valued by 'the market'.