Look at the context, Blessed are the poor in spirit for theirs is the kingdom of heaven -Matt 5:3. Blessed are those persecuted for righteousness sake for theirs is the kingdom of heaven - Matt 5:10. Strongly suggests inheriting the earth as a possession as kings.
Having said that, who wrote it, who translated it, who decided this bit should go in the Bible canon and not be assigned as apocryphal, which verses in between were discarded etc etc.