There was an 2021 Lineup presentation held today in Tokyo where they had announced the list of movies that will be released in the year 2021.
The list included "Kamen Rider Saber the Movie (Temporary Title) / Kikai Sentai Zenkager THE MOVIE (Temporary Title)" which is planned to be released in Summer and "Kamen Rider the Movie (Temporary Title)" (Reiwa Generations) in Winter.
Shinichiro Shirakura had said that "For next year's TV Broadcast and Movie Release, we are planning a big project as part of 50th Anniversary. Kamen Rider Saber which is broadcasting right now will be a big part of it. It's not going to be a Spin-off. We want to make it suitable for 50th Anniversary".
Looks like Toei is not planning to release anything in the April slot this anniversary year.