Released in May 14, 1996, Fire Emblem Genealogy of the Holy War, also known as Fire Emblem 4, is the oldest Fire Emblem game that has yet to receive a remake.
Just like every Fire Emblem game until Fire Emblem The Blazing Blade, also known as Fire Emblem 6, released on Game Boy Advance in 2003.
Nintendo will hold in a few hours its special Nintendo Direct for E3 2021, and many fans believe this could be where a new Fire Emblem will be revealed, most notably a remake of Fire Emblem 4 Genealogy of the Holy War.
I could definitely see an Echoes version of Fire Emblem Genealogy of the Holy War being announced soon.