A preiview for the January issue of Nakayoshi, a shojo (girl) manga magazine, gives us more info on the long awaited reboot of Carcaptor Sakura. NHK will be broadcasting the Clear Card Arc of Cardcaptor Sakura in 2018. The show will revisit Sakura during her middle school years. It will focus on the story released by Nakayoshi this July in honor of the manga’s 20th anniversary.
So it’s not exactly a reboot but kind of a continuation from where the show left off in a way.
Part of the flyer says (Rough Translation):
TV Anime Series
Clear Card Arc
2018 January NHK will broadcast.