An originator could lease their work, but only as long as they own the rights to it. Perpetual leases wouldn't be possible. When an originator dies before their copyright does, for instance, the work is transferred to a separate entity and thus has a defined time limit.

Wouldn't everyone just create a corporation and assign all their work to that from conception? Corporations never die.

Corporations cannot be originators.

If you assign work to a different entity, it is no longer owned by the originator, and subject to a shorter copyright term.

Are you saying that's how you would solve it, or that's how things work?

Employees create content all the time that is copyrighted by default by their employer and never by the employee.

That's how I would solve it, yes.