I would think that a cheaper (or multiple cheaper) versions could be made if they don't require the long lifespan and reliability that previous launch costs inflicted. Once Starship is going, and if it proves to be as low cost as the current projections, I could see multiple space telescopes being designed cheaply for a launch every year, each one designed in a narrow configuration that serves a specific purpose. But I really don't know what all goes into making a space telescope so expensive currently.