The Julian calendar did not end with the Gregorian reform. It remains the liturgical calendar of the Russian Orthodox Church, the Serbian Orthodox Church, the Georgian Orthodox Church, the Jerusalem Patriarchate, and the monastic republic of Mount Athos, which is why Orthodox Christmas is commonly kept on the seventh of January by Gregorian reckoning, thirteen days after the twenty fifth of December the calendar itself still calls it.
Other Orthodox churches, including the Ecumenical Patriarchate of Constantinople and the Church of Greece, adopted a Revised Julian calendar in 1923 that realigns fixed feasts with the Gregorian dates until the two diverge again in 2800, while continuing to compute the movable feast of Easter by the older Julian based Alexandrian method regardless. The result is that Orthodox and Western Easter can fall on the same Sunday or several weeks apart depending on the year, purely as an artifact of which calendar underlies each computation.
The 1923 reform also produced a lasting split. Old Calendarist communities broke from the Church of Greece and other reforming churches specifically to keep the unrevised Julian calendar, and those communities remain active today, so the Julian calendar is not a single settled inheritance but the object of a live and ongoing ecclesiastical disagreement over which calendar a church should keep.