Are you sure, reptiles? I'd think in order to extrapolate next we'd have to first pinpoint, "why humans?" I think Immanuel Kant said what makes humans unique is it's "unsocial, sociability." Kant himself was trying to get at the sources of good and evil but as he and philosophers of the time often did he tied in the scientific. Clearly this is before Darwin so he was uniquely focused on the remarkableness of man over the rest of the animal kingdom.

It's ok, all this "God" stuff because what is doing the selecting is irrelevant, whether by God or by evolution, whatever made up special selected us. So let's assume for now that Kant did a good job boiling it down. It's not music appreciation or our overall cognition, it's our unsocial sociability that has led to our domination of the planet and enabled us to reach our current potential.

I think reptiles are a poor choice to make the bet. This is likely a probabilistic equation at best so the job here is to make the "best guess" out of an array of possibilities. We'll assume the catalyst for such an elevation of a species will be a mass extinction event, just so happens we're in one now. Provided we die off with the things we're killing around us, the war is over and a new era of biodiversity will emerge. Previously it was mammals who were able to take its micro-advantages and scale them to this level of gluttony that enabled man to eventually emerge. They had the flexibility and complexity to fill out the planet and dominate it.

So who is the most flexible of the small land animals that can re-populate the planet? Frankly I would assume another mammal. Large and complex are out the window. You want a candidate that is robust, small and has the greatest level of cognition. I think primates will die off, but there's a chance a small monkey survives, I think they're too high on a complex food chain.

Elephants are too large and are on their way out form our activity, so I think they're out. Dolphins and other sea mammals could redevelop limbs and take over but I think more likely we're looking at a future of pigs or rats. These guys are small, intelligent, can survive almost anywhere and are prolific breeders. Assuming we're not wiping out all of mammalia, I think these guys are the most likley emergers of the next intelligent species.

A close second will be any number of species of birds. They instantly get a back seat to any mammal because they obviously had their chance to evolve along these lines. Sure crows are interesting but they're not inventing computers. We have to assume there's a fundamental design flaw that kept them from progressing. That being said, time cures evolutionary wounds. If all of mammalia is gone, birds are next.

So why not reptiles? The just don't have the complexity or intellectual capacity. I think they're 10s of millions of years behind the next candidate and what reptiles are surviving if everything else we're talking about is dead?

In fact, I think insects are ahead of reptiles. Look at ants. Complex social unsociability. Yesterday I was in the garden I pulled up a rock and BAM there was the egg chamber. Ants sprung into action, they'd grab an egg and backflip into one of the newly exposed holes to the colony. Holy crap. This ant knew he was exposed and that the egg needed protecting. This wasn't "go out get food come back" this was a complex reaction. OMG. Insects have more going on than people give them credit.