Shin Evangelion Gekijō-ban :|| aka Evangelion: 3.0+1.0, the fourth and final film in the Rebuild of Evangelion tetralogy finally has a confirmed released date after Anime Mojo shared the
first teaser for the project in July 2018.
Unfortunately, the project is still a ways off as it won't hit Japanese theaters until June 2020 as revealed by the official Evangelion Twitter account. The third film, Evangelion: 3.0 You Can (Not) Redo. was released in 2012, meaning mecha fans will have waited 8 years for the film's to finally be completed.
The new films are the second "retelling" of the original 26-episode TV anime series that wrapped in 1996. Two compilation films followed in 1997 before the new tetralogy kicked off in 2007 with Evangelion 1.0 You Are (Not) Alone.
Without going too far into spoiler territority, there are slight differnces within each retelling that's lead to a rather convincing fan theory that each story is set in a different universe as the concept of a multiverse is introduced in the final episode of the TV anime.
Furthermore, each retelling appears to be director Hideaki Anno snarkly addressing fan complaints of the original series- providing a twisted version of the ending fans garishly begged for. Crunchyroll has a rather succint video below explaining things in greater detail but if you've never seen the series, beware of spoilers.