White Woz's Future Note has turn into a similar looks to Oma Advent Calendar.
This book is named "The Legend of Savior" A new form of Future Note, and i think it will basically function the same way as Black Woz's Oma Advent Calendar and maybe still retain the same function as Future Note to manipulate future events by writing it. And yes it will appear in Kamen Rider Zi-O NEXT TIME: Geiz, Majesty. And Geiz Myokoin (currently named Keito Myokoin, his new name in new timeline of 2019) probably going to have the same journey as Sougo but as a "savior".
Black Woz: I don't wish to rejoice...but my pride...--IWAE! The one to save those suffering from the darkness. He is the savior who brings light back to the future! His name is Kamen Rider GeizMajesty! Truly a moment of nativity.
And also Keito Myokoin (Geiz's new name) will have to collect all Secondary Heisei Rider Ridewatches including Kusaka Masato (Kaixa), Terui Ryu (Accel), Akira Date (Birth), and last but not least the thief himself Daiki Kaito (Diend) including fighting Kyoryu Greeed, multiple Kasshines, and Another Diend.