Last year when the Final Fantasy VII, IX, X/X-2, XII HD remasters were announced for rerelease on Xbox One & Switch, Final Fantasy VIII was noticeably missing but later announced for a 2019 release. The original director Yoshinori Kitase explained in an interview with Famitsu why its remaster was delayed.
Source: N4G PC Final Fantasy VIII Director Yoshinori Kitase Explains Why It Was Late To The Remaster Party