This is quite false. All that has happened is that we've (to some extent) replaced genes with memes, and memes evolve just like genes do.
Evolution is still underway, actively and blindly selecting individuals and ideas with equal efficiency.
> There's not much of that happening in the homogenized urban setting where the majority of people live, and will live for the foreseeable future.
I'll just give one example that falsifies the thesis -- what is called Asperger Syndrome (AS). A thousand years ago, someone having the behaviors associated with AS might be at a significant evolutionary disadvantage compared to someone who could pick more olives up off the ground. But today, the AS behaviors represent a distinct advantage because the environment has changed in ways that favor that mental wiring, such that a number of AS "sufferers" (to use the psychological terminology) are famous -- Bill Gates, Albert Einstein, Thomas Jefferson and many others identified as having AS.
AS is so obviously an advantage in modern times that another psychological school of thought called "Grit" goes so far as to describe the same behavior pattern as an advantage:
http://en.wikipedia.org/wiki/Grit_(personality_trait)
Of course, the Grit people don't call it AS or even mention AS, they just say how advantageous it is to have the intense focus and obsession with only a few activities (or even one) this behavior produces in many modern success stories.
It's evolution at work. I'm sure many more examples could be found, less dramatic than this one.
Evolution is the central theory of biology, and it didn't just stop for human beings when we built the first TV set or began dwelling in arenas of pure thought -- quite the contrary.
Unless people with AS / Grit have more children than those without, there's no selective pressure to increase the prevalence of the trait in the population. You could consider health of the children - so maybe you should count great-grandchildren rather than direct children.
BUT - I agree that evolution probably hasn't stopped - it just is selecting for different traits than it did 15,000 years ago. What exactly is being selected for in US in 2014, I can't say.
You can hear his arguments and draw your own conclusions: https://www.youtube.com/watch?v=UkuCtIko798
In the very, very long run, who knows.
But int the timescale of tens or even hundreds of thousands of years I don't think there will be any natural selection process that will apply to the current status of humanity as a species, unless for some reason civilization will fall and humans are scattered throughout the globe.
We've pretty much stopped evolving as a species through natural selection events. There's not much of that happening in the homogenized urban setting where the majority of people live, and will live for the foreseeable future.
Actually, having the current civilization as a substrate for the species does change the playing field considerably from what it was a few thousand years ago.
As for biodiversity creating some sort of 'better adapted species' to take over our position - the sad truth is that biodiversity is in rapid decline, and I don't know when it will stop. We are not killing the planet per se, only... homogenizing it and making it fit for humans.
In a million years, sure, who knows what will happen. But in the current mass extinction event - if we can feed the the human species it's very difficult for me to imagine anything will replace us when the timescale is only the current estimated age of the species.
Prepare to be rickrolled for the next 100k years. Or maybe we will move into some dense compute substrate made of exotic materials.