XboxEra had a Podcast a month or so ago where one of them mentioned he heard the reveal event is in April/May but Idk how reliable he is. I reckon they'll reveal another IP too, most likely Forza Motorsport as Phil did say he can't see them not revealing a game or two for all their future major events from now on.
Give me that rumored Fable game and I will be happy. I'd even be all for a Gears of War Marcus Fenix Collection and / or a Fable Trilogy for the Xbox Series X. It would help pad the lineup of the console and give people who have never played the series before a chance to play them at a reasonable price.