And There is a final,ethical consideration. Even it we learn how to reproduce an example of an extinct species, that individual could never have a normal life. Its natural environment is most likely gone and it would have no parent to show it how to behave as a member of its species. So the animal would remain a curiosity and probably live out its life in a zoo. People question whether it would be ethical to revive one of natural's creatures for suck a purpose.
Only time will tell if scientists manage to carry out their ambitious plans. Even if they manage to overcome the scientific problems, they may face opposition from governments or society. Some even feel it might be more worthwhile for us to focus our efforts on conservation and take care of existing species, so they don't also go the way the woolly mammoth.