There have long been rumors of the Aurora as an even faster, more advanced surveillance plane to succeed the SR-71. Certainly it doesn't seem to make sense for the US to have decommissioned the SR-71 if there was no replacement available, other than the older, slower U2. While satellite surveillance is much more advanced than it was when the SR-71 was conceived, it still doesn't provide the flexibility of a plane, in terms of the ability to overfly when and where we want.
I find it amazing that we were conceiving and building the SR-71 all those years ago. While technology has made great leaps since then, the SR-71 was developed closer in time to the Wright brothers' first flight than to the present day. It was designed in a time when computers ran on vacuum tubes, and when the entire computing power of the Department of Defense combined (or certainly the Skunk Works) was probably less than the average smartphone today. Despite that, it remains the fastest plane ever built (at least that has been revealed to the public), a record it has held since 1976. Just remarkable . . .