Jesus" mention of a long time passing probably suggests the time between His ascension and His second coming (cf. Matthew 24:48; Matthew 25:5). Thus while the slaves in view are those living during the Tribulation, with which the whole Olivet Discourse deals, the parable has meaning for all Jesus" disciples who anticipate the kingdom. This is true of all Jesus" discourses in Matthew. [source][source][source]
The first slave received a verbal commendation from his master, increased responsibility under his master, and joy with his master ( Matthew 25:21; cf. Matthew 24:46; John 15:11). He would exercise his increased responsibility and enjoy his joy in the kingdom and, I assume, beyond it when the earthly messianic kingdom moves to new heavens and a new earth ( Revelation 21:1 to Revelation 22:5). The second slave received the same verbal commendation as the first slave, and he received increased responsibility and joy commensurate with his God-given capacity ( Matthew 25:23). [source][source][source]
"You don"t "retire" from being a disciple." [1][source]