Scripts in current use are almost all used by very large numbers of people. A handful are used by a few million, a few by a few hundred thousand. Samaritan is used by a community numbering in the hundreds, which puts it at the far end of that distribution with almost nothing beside it.
It is worth being exact about what living means here, because the word gets used loosely. This is not a script preserved by enthusiasts, nor one reconstructed by scholars from inscriptions, nor one revived after a break. It is taught to Samaritan children as part of an ordinary education, used to copy the Torah by scribes who learned the work from their families, used in the liturgy, used for inscriptions and for correspondence, and encoded in the international character standard so that it can be typed and published. Every function a writing system can have, this one has, at a scale of a few hundred people.
That combination, an unbroken line of use running back to the alphabet of Iron Age Israel, carried by a community small enough to count, is not matched anywhere else. It also means the script is exposed in a way a large script is not. It depends on one specific community continuing to teach it, and there is no reservoir of other users to fall back on.
The letters end here, at taaf. What began as the alphabet of Israel before the exile is still being written, right to left, twenty-two signs, by the people who never changed it.