Near as I can tell, the only proof for this silly claim that Richard Dawkins-style confrontational atheism is over and done, supplanted by a kinder, gentler version, is the author's say-so. But okay, let's see if there's any fire behind this smoke by checking a standard that I happen to know a li'l bit about by virtue of one of my jobs: book sales.
In a nutshell: I would consider any book with an Amazon sales ranking of 100,000 or lower to be something I could sell within a few days. So how do some of the New Atheist authors fare as of this moment? How thoroughly have consumers rejected the rudeness of Dawkins, Dennett, Harris and Hitchens via the power of their purses?
The God Delusion: #713
God is Not Great: #987
Free Will: #3,650
The Portable Atheist: #3,729
The End of Faith: #5,559
The Magic of Reality: #5,579
Letter to a Christian Nation: #8,861
The Greatest Show on Earth: #14,369
The Moral Landscape: #32,114
Breaking the Spell: #35,157
Unweaving the Rainbow: #193,629
Even the "weakest" of the bunch is something I'd be glad to get hold of. These books have all been out for a while, too, so this isn't a case of a just-released book rocketing up the rankings by virtue of everyone buying it at once, or of a dramatic sales bump following the news of an author's death (man, you should have seen how much Hitchens' books were selling for a little over a year ago; death really is a good career move). The reading public can't seem to get enough of this stuff.
As the old saying goes, money talks and bullshit walks, so if Theo Hobson presented me with brand-new copies of all of these books, I would snatch them out of his hands faster than he could blink and turn a tidy profit on them by the end of the week while he sputtered and harrumphed about how "nobody" is reading them anymore. But I imagine a devout believer is no stranger to telling himself what he wants to hear.