I had seen some mention of resurrecting mammoths from fossil DNA. The problem there is that there doesn't seem to be any fossil *mitochondrial* DNA; the two sets of DNA produce proteins that work in *very* close concert - close as in a couple of angstroms off and the electron transport chain fails which is, as they say "incompatible with life". Elephant mitochondrial DNA probably isn't close enough.
If they're focused instead on turning elephants into 'new mammoths', why not just make new elephants - ones that have much smaller tusks - or maybe blue tusks. The human threat to elephants is the price of ivory - take that away and they might be fine where they are.