I think humans could adapt to the conditions on Pandora and evolve to resemble the Na'vi.
Evolution is a process that can take long periods of time and is influenced by various factors, such as environment, genetic predisposition, and competition for resources. Evolutionary theories suggest that species can adapt to different environmental conditions over many generations.
Accelerated evolution on a level such as the Na'vi appearance - is not possible in one generation, it is a long process. But hey, what is genetic manipulation for?
Photoshopped version