Not just the Fate/EXTRA Last Encore anime comes in 2017 but another, novel port version also announced the Fate/Apocrypha.
The novel released in 2012 and until now 5 volumes released and in 2017 comes the Anime version.
The exactly release date of the anime is not clear but the first promotion video already released what you can watch above (VPN requires because the video blocked outside of Japan). Accroding to the press release the story going to follows the original novel with all the original characters. Until more information please stay tuned!