You are going to have a long wait if you are waiting for a US moon based telescope. Right now we have 500+ billion and growing budget deficets. The dollars is falling and in a few years all the retiring baby boomers will break the US treasury bank. No body is going to spend unteen billion dollars on a mission to the moon or a new space telescope when the nation is flat broke.
It is either save Hubble or forget about a serious American space telescope for at least a generation.
The Chinesse are launching a smaller space telescope at about the same time Hubble will be burning up in the atmosphere. Think about that.
True enough, Hubble is doing some great science.
But it's also a satellite, and satellites get old and eventually die. Whatever else it may be, Hubble is also an aging spacecraft. It's got a bunch of holes in it from debris and micrometeoroids, and its MLI blankets are old and discolored (which means it's warmer than it used to be). Its electronics have been bombarded with radiation for close to 15 years, which takes a toll even on shielded components. It's been through a bunch of thermal cycles, which causes stress and that affects things like connections and structure.
You are going to have a long wait if you are waiting for a US moon based telescope. Right now we have 500+ billion and growing budget deficets.
You have to be careful when you start tossing costs around like that. What you're really proposing is further Shuttle missions to repair Hubble. Well and good, but bear in mind that it cost over $300 million just to launch a Shuttle even before Columbia burned up -- it'll cost more now. The replacement hardware might cost more than the launch itself (as has been the case in the past).
At some point, it becomes cheaper to build and launch a new telescope, than to maintain the old one. NASA's cost numbers suggest that the threshold has already been reached.