Really, they should be already building 2nd James Webb. I am sure even 10 of them would get 100% utilization for their whole lifetime. I can only imagine what kind of needless political game is happening around prioritization of time slots for it.
Or start working on next-gen, bigger, more resilient etc. It costs peanuts compared to any significant CERN upgrade and we have so much room to progress in astronomy (aka understanding our home, this universe) just by getting more data and resolution.