It takes about fifteen years from concept studies to launch for a Hubble-class space telescope. I guess you could make it in ten if you just chose to replicate Hubble's instruments and if NRO had another spare Keyhole stashed somewhere...

The NRO donated two and parts for a third to NASA in 2012. One is apparently being used for the Roman Space Telescope, which would seem to leave another and a primary mirror of a third still unused.