why spend $1B on Hubble upgrade?
I'm against any Hubble effort other than a crewed return & refurbish, presently outlawed by NASA.
If we could somehow spend the $1B upgrade funds building a 100 meter OWL class scope, we'd get better science return than by continuing Hubble, given that Webb is a go. Adaptive optics et. al. has absolutely revolutionized ground based astronomy. Forget those girly mon 30M scopes in the planing stages; go build a 100M and revolutionize the science again.