What awaits the Cygnus spacecraft when the US runs out of Russian RD-181 engines

In August, the flight of the Cygnus cargo spacecraft to the ISS is to take place. But planning this flight for

the moment remains unclear due to the fact that the United States may not have any Russian RD-181 rocket engines left. Discuss

And it's not just the sanctions. The first stage of the Antares medium rocket, carrying a cargo ship and containing two RD-181s, is produced in Ukraine.

Since the beginning of the special operation, the availability of components for assembling the stage and engines has been a big question.