Humans aren't suppose to evolve unless there's a mechanism, perhaps a catotrosphic event, which forces people to compete with limited resources. Then, there's selection for particular traits based on those who survive and reproduce, ie - people physically unable to compete for resources, or not smart enough, would not reproduce, and there genes would not become part of the gene pool. Evolution is true, but evolution is no match for the first world we enjoy living in. I'd say on a macro scale humans are devolving physically.

Imagine if the grocery stores went empty today, would it be possible for modern day humans to adapt to any resemblance of hunter/gather type living? We are too accustomed to our current lifestyle, supplemented by technology. That's the same reason why there would never be an organism to evolve further than humans. Humans would just use technology to destroy anything that becomes a threat (after all, we compete for the same resources).