"What science tells us is that we are but one among hundreds of millions of species that evolved over the course of three and a half billion years on one tiny planet among many orbiting an ordinary star, itself one of possibly billions of solar systems in an ordinary galaxy that contains hundreds of billions of stars, itself located in a cluster of galaxies not so different from millions of other galaxy clusters, themselves whirling away from one another in an expanding cosmic bubble universe that very possibly is only one among a near infinite number of bubble universes. Is it really possible that this entire cosmological multiverse was designed and exists for one tiny subgroup of a single species on one planet in a lone galaxy in that solitary bubble universe? It seems unlikely." (In the hardcover edition, pages 160-161.)
What can one say? People have different opinions about the evidence.
In fact, Shermer has flip-flopped from strong belief to disbelief, so his "unlikely" claim doesn't have much weight behind it IMO, if some years ago, when he interpreted the evidence differently, he'd probably be saying "very likely".
What Shermer seems to be saying is that because there are sooooo many, therefore it probably isn't designed. That is probably some type of fallacy.
So to answer Shermer's question, Yes, it is possible. Design is possible because we see design-like stuff (whether it is truly designed or not is another story) around us all the time.
Now what?