While I think it would be very interesting to see what a mammoth would look like in real life, I have some concerns as to the welfare of one should they succeed.
A. Mammoths lived in herds. Would they let this mammoth stay with it's surrogate elephant herd, or would they (most likely) have it in some exhibit all alone.
B. Habitat. Would they be able to keep a mammoth in a habitat that would see to it's needs? How much trial and error will the poor thing have to endure while they figure that out.
C. Food. We can guess as to what a mammoth would eat, but what if there is something more specific that it would need that we don't have access to?
I think if they have the ability to do this, they should instead bring back animals that humans have made extinct only recently, that is, animals that would be able to survive in the present climate without human assistance and that would be able to use their instincts to relate to the current world. The Passenger pigeon comes to mind. As does the Dodo, or any number of species humans have eliminated in the last 200 years or so. Google extinct animals and birds. The list is quite long.
~ Of course. I can just see it now. BYC folks incubating dodo eggs...