It was meant as a joke.
My real guess is that "they" will continue to use the SR-71 as long as they want/need to, but "they " don't have to inform us about it. I would also assume that there is already a newer version of something flying that's about to replace the SR-71's replacement. After all, they usually don't tell the public about what they have until it's been a very long time in operation.
From what I've heard, "they" are usually about 20 years ahead of the technology that has been revealed to the public. You don't want your enemies to know everything that you have.
And as Tom stated, you can't just move satellites to where you need them. But you can get a plane overhead in a matter of hours.