NASA's auditing body, the Office of Audits, has produced a report detailing the agency's commitment to replacing the International Space Station (ISS) with one or more commercial space stations once the orbiting lab is retired. Despite still being scheduled for 2024, all indications are that the ISS's operational life will be extended to 2030, which is when the agency is assuming it'll be able to hand off human occupation of an on-orbit science facility to a private company.
This audit basically details the current costs of maintenance and operation of the ISS, and also explains why it thinks that there will still be an essential need for a research facility that can provide a test bed for prolonged human exposure to space, as well as for development and demonstration of tech key to helping people explore deep space, including the establishment of a more permanent presence on the moon and exploration of Mars.
The conclusion is that NASA hopes to see a commercial station operation by 2028 in order to give a period of two years of overlap before the anticipated retirement and de-orbiting of the ISS. That timeline presents clear risks, however, in part because of "limited market demand, inadequate funding, unreliable costs estimates and still-evolving requirements."
The good news is that recently a lot of companies seem to be interested in pursuing the development of commercial orbital destinations. A partnership between Nanoracks, its parent company Voyager Space,and Lockheed Martin aims to produce one by 2027. Blue Origin hopes to launch its Orbital Reef station with Sierra Space and Boeing by 2030 at the latest, while Axiom is already progressing with its plan to send up modules that will attach to the ISS before separating and self-orbiting as its own station by 2028.
You can read the NASA Office of Audits report in full below: