In case they succeed at this, I wonder if it would be feasible to do something similar to bring back the giant ground sloth, extincted roughly at the same time frame as the mammoth. One thing that helps the mammoth is they lived in cold climates, so we found a lot of well preserved DNA samples. I think the ground sloth lived in areas with hotter climate, where DNA doesn't preserve well.
Some scientists doubt that the modern world needs species that became extinct several thousand years ago. After all a lot has changed in nature during this time