They might not be quite as helpless as some of our domesticated-for-millennia animals (even those can go feral and survive), but at least some individuals would face a difficult adjustment. Thaxter shows no sign whatsoever of fear of humans, and expects food to be brought to him; he'd probably learn quickly enough to hunt when he's hungry, but the fearlessness could serve him ill. (Of course, many of our chameleons are far removed from their native environment as well - chams can survive and thrive in Florida or Hawai'i, but it's hardly their native haunt, and Michigan and the UK would present considerable problems of their own...)