I'm sure we'll see something like her again I just think there won't be another aircraft like her that will have a pilot. I would say it would likely be unmanned.
Only now are these technologies coming out of the black world. Pentagon's 2009 budget request includes $750M for the DARPA HTV-3X Mach 6+ hypersonic vehicle. First flight is FY2012.
Hmmmm.... That's awfully quick turnaround for such "high risk technologies" that supposedly have never seen the light of day.
The ostensible reason she was retired was rising maintenance costs (the newest SR airframe is/was over 30 years old), fewer spare parts supplies, and a lack of meaningful strategic targets for the -71 to surveille since the dissolution of the Soviet Union. However, there are others who suspect that there was more to it than that; that perhaps there is already a more advanced strategic surveillance platform in operation (Aurora?). There is very little evidence for this, and more evidence to the contrary, but that doesn't stop people from speculating.
Twas a great aircraft, a tad bit expensive, but effective. I heard from an unconfermed source that the US was testing an uma with mach 10 capabilities (like stated above), not to mention the U-2 along with spy satillites provide effective intel.