Board Thread:General Discussion/@comment-7669924-20151018030852/@comment-26987392-20151018184024

Dragons' can be physically killed by mortals, but only dragonborn can truly, permanently kill one by devouring it's soul. The same rules apply to dragonborn.

However,

AzuraKnight wrote: Being prophesied as the Last Dragonborn could mean there won't be anymore. that is possible true.