Shin Evangelion Gekijō-ban :|| has been a long time coming. Evangelion: 3.0 You Can (Not) Redo was released in November 2012 and the fourth installment was slated to arrive in 2015 originally.
However, Neon Genesis Evangelion creator and director Hideaki Anno fell into a depression following the release of the third film due to its many troubles. He actually vowed that he would never direct again but was subsequently persuaded to direct Japan's Shin-Godzilla reboot.
It seems that experience reinvigorated Anno to the point where he felt comfortable enough to return the rebooted, four-part Evangelion film series.
Presently, Evangelion: 3.0+1.0 is slated for release in 2020.