Per a release from MiLB:
“In light of the current coronavirus outbreak, and after consultation with medical professionals and our partners at Major League Baseball, Minor League Baseball will delay the start of the 2020 Championship Season. We will continue to monitor the developments and will announce additional information about the 2020 season at a later date. We will work with Major League Baseball and our community partners to resume play as soon as it is safe to do so. The health and safety of Minor League Baseball fans, players and executives is our top priority, and our thoughts are with those around the world who have been affected by this outbreak.”
It's unclear why Minor League Baseball would refer to the season as "the 2020 Championship Season".
In a press release, the Phillies' Double-A affiliate, the Reading Fightin Phils stated the following:
"The R-Phils will keep our fans and partners updated as any further developments occur. Rest assured that the R-Phils will do right by our fans and partners as we all navigate these uncharted waters together."
Additionally, the remainder of the big league spring training schedule has been cancelled, as has the minor league exhibition schedule.
Per a source, it remains a possibility that there could be exhibition games played before the regular season at various levels begins.