I am not a lawyer, but dear gawd, how would that even work? I can imagine a huge number of domains where a time limit would make interaction unfeasible.

- I am buying my house for perpetuity, not leasing it for a limited period

- I'm a photographer, you're a model, I want a model release that's unlimited or it's not worth my time and risk to deal with you (this is usually framed as "rights" or "license", but signed in form of a "contract", similar to what the FaceApp would likely do?)