No doubt, satellites can perform the role of the SR-71.
My point is that the system we have in the US could not create a new SR-71 class airplane right now, in my view. It would run over budget, miss the performance targets, and be cancelled.
Actually, satellites alone can't do what an SR-71 can. Satellites aren't an ad hoc intelligence solution, since they are periodic in their orbit and can't image something they aren't on-station to see. But combined with other tech, they replace the SR-71 nicely.
As to your "point", it's trivial to say "we can't do something" when we haven't tried.
My point is that the system we have in the US could not create a new SR-71 class airplane right now, in my view. It would run over budget, miss the performance targets, and be cancelled.