Well, this can go two ways for me. First, we could let evolution take its course and eradicate these creatures not even fit enough to breed, like they biologically deserve. Being able to reproduce is not just a requirement for a species' survival, it's a requirement for being considered alive in the first place. Basically, if these pandas can't screw, screw them.
But with regards to evolution, humanity has always been more, "Let's see how we can use this," rather than, "Let's just let it take its course." Case and point: doggies. We took wolves, made a completely new species out of them, and varied that species so much so that its largest subspecies is hundreds of times larger than its smallest. It would be like if there was another subspecies of human that was the size of a two-story house.
My point being, for people, evolution is more of a tool, sometimes even a plaything. It's one of those forces of nature that we have a lot of control over. If we want a species to live, we have the means to do so. If we want a species to die, we have the means to do that too. I personally don't really care about pandas. They're a waste of resources that could be much better spent. But I'm not the one with the reins, so whatever.