Much more common in the US, is to use a family life. Example: “this trust will last as long as the life of Tom Jones or any of his now living decedents, plus 21 years.” It could be a trust, rental contract, or some other type of contract. Many states have gotten rid of this old 21 year rule, and allow 90 years, 360 years, or even 1000 years.

The point is to not keep property, especially real estate, bound up forever.