1908 - Kent Nelson is born.
1920 - 12-year-old Kent joins his father on an expedition to open the supposed resting place of Nabu, the ancient sorcerer. His father is killed opening the tomb, & Nabu, immortally bound to his helmet, takes pity on Kent, taking him in as a student.
1940 - 32-year-old Kent leaves Nabu's tomb possessing the helmet of Nabu & discovers that the world is in chaos. He first becomes Doctor Fate.
1945 - WW2 ends.
1947 - 39-year-old Kent retreats into Fate's Tower, where his aging stops.
17 years ago - Inza Cramer discovers the tower and convinces Kent to take her on as an apprentice and assistant.
5 years ago - Inza Cramer, under the influence of the lord of chaos T'Giian, leaves Fate's Tower. Her location is hidden.
4 years ago - Inza Cramer is overwhelmed by her amulet, becoming the avatar of T'Giian. The Justice League find Kent in Fate's Tower. He battles Inza, saving her from T'Giian. they are married by Nabu, & return to the tower.
Doctor Fate is an iconic DC character. During the height of the golden age, the silhouette of his helmet was just as famous as Batman's cowl. His career stretches all the way to the modern age, but he never cleanly separated from the WWII era hero. Even as new versions of the character are crafted, the true concept for Doctor Fate will always be rooted in his history with the wartime Justice Society. Even in his modern incarnation, he's best as a reclusive mystic, devoted to the balance between Order and Chaos from within his tower. With such a simple explanation for the character's longevity as 'he stops aging inside the tower', there's just no need to pass on the legacy to others, so we're keeping Kent and ignoring Eric & Linda Straus, Jared Stevens, Hector Hall, Khalid Ben-Hassin or any of the other various incarnations of Fate.
One thing we ARE doing is deliberately re-imagining his relationship to Inza Nelson, his wife. There's precedent for Doctor Fate to join the modern Justice League, and for there to be a female Doctor Fate. Inza herself even wore the Helm of Nabu for a time, if I'm not mistaken. We can combine these ideas, having Inza take on the role of the modern Doctor Fate and join the League. We've deliberately altered the nature of their relationship, making her Kent's long-time apprentice and assistant before she dons the Helm. By making this act of rebellion the result of the machinations of T'Giian, we get to create a story where the rest of the League has to find Kent to get him to help them defeat Inza. That story alone makes the continuity change worth it.