Great post. For a couple decades now, there has been a group trying to lobby the gov't to make a new National Park called Buffalo Commons. The point being to restore some of the grasslands/savanna of the Great Plains, and therefore restore the natural habitat of the bison. This place would be all the more amazing if it also contained saber tooth cats, mammoths, and giant beavers. Imagine being able to go on a safari in a few hours' drive instead of having to fly to Botswana!

There is a huge problem with de-extinction, however, and you touch on it a bit in your post. That is, an organism is way more than just its DNA. All of the biomolecules are important, but especially the transcription factors and non-coding RNAs. This is important, because they are largely contained in the egg, and as we would have to use a cross-species egg (e.g. elephant egg to restore the mammoth), there could be some major biological implications. There was news recently about de-extinction of the gastric brooding frog, but the animals apparently all died in the tadpole stage. Its a step forward, but I fear that the problem is one bigger than DNA, perhaps an intractable problem. I hope not.