Satellites are more capable these days, overflights outside of a military action are political suicide, and most combat is handled at long
range (with an emphasis on Beyond Visual Range). The only reason to produce such an aircraft would be for those records - such an aircraft serves no
practical purpose today.
This, I have to disagree with to quite an extent.
Any halfway competent military power is more than capable of tracking satellites. Sure - their trajectories can be altered to some degree, but they
are not carrying a ton of fuel, and rapid shifts in trajectory are very costly to the craft's service life.
The advantage an aircraft has (manned or not) is that it provides very little/no predictability. The enemy no longer has the ability to know your
windows of vulnerability.
Of course - one could resolve this by pulling a Gandhi and threatening to blot out the sun with spy satellites, but with many nations developing
anti-satellite weapons, they can reach out and swat them down if they really don't want to be seen.
Satellites also have vulnerabilities in their data relay systems. Incidents like the Fort Hood shooting have demonstrated there is a very real threat
to national security on our own soil coming from insurgents in our own ranks. So, even strategic targets within our own borders are not impossible
for a foe to strike.
For this very reason, it is highly likely that some officer(s) have a restricted access research program designed to develop the technology to address
the vulnerabilities in satellite coverage.
The SR-71 was a marvel of engineering at the time - and even now has no real equivalent. Any possible product of the programs alluded to above could
never begin to touch the service record of the SR-71. Anything that is running would be one or two demonstrator aircraft that end up taking up
missions for special forces units.
They are there merely to make sure we don't completely lose the ability, and have the plans already drawn up and tested if we need to put them into
production. That is how a lot of the "black" programs work these days - there is no perceived threat worthy of trying to develop, service, and
field and entire "black" fleet of aircraft.
But, I would not go so far as to say they do not have an aircraft that trumps the SR-71. However - going much faster than the SR-71 would cause you
all kinds of hell in getting a clear optical, thermal, or radar image (we take more than just black and white pictures now). You would want a
trans-atmospheric vehicle. Congress has aerospace fighter research on the 'white' budget.
Again - that's not suggesting we have the Pillar of Autumn up there spitting out Longsword fighters or some nonsense, cool as that would be. I'm
merely stating that there are plenty of people writing checks with that sort of stuff in consideration for us to rule the idea out, completely.