it'll never happen. Those satellites, collectively known as "National Technical Means of Verification" in treaty lingo, are very expensive and limited resources. The low flyers (the ones with the really expensive optics) have a limited operational life and a price tag said to run into the 9 figures. There's virtually no way NRO, CIA, DIA, or any of the other TLAs (three letter acronyms) would agree to give up any of those assets short of a direct presidential order. At the same time, I wonder how well they'd work in regards to focusing. Their optics are designed to work at a distance of few hundred kilometers. How well would they focus on something at effectively infinite distance?

Now, some of the technology on those satellites could prove very useful for astronomy. The security issue is keeping the technology under wraps while using it for scientific purposes. Virtually everything NASA does is in the public domain. Simply putting the black world technology on scientific satellites would likely mean compromising the technology by exposing its capabilities and thereby its limitations and vulnerabilities. It might be possible to put some older spysat technology to scientific use without doing damage to our current and future systems, but I can see the security people opposing even that.