There is almost certainly an operational spy plane to replace the SR-71. Top Secret stuff but there are a LOT of credible reports of strange super fast mysterious delta shaped planes zooming around Nevada/Utah/Idaho Sky's. I've seen some mighty interesting pictures of "beads on a string" contrails left by SOMETHING with some kind of a pulse detonation engine. Satellites can't do EVERYTHING, FOR SOME THINGS YOU NEED A SPY PLANE !

You can bet the Air Force wouldn't cancel the SR-71 unless they had SOMETHING to replace it ! (your tax dollars at work... )

Cheers,

Slim