Thanks all regarding the update to the time period with the earthly hope teaching began. 1935 would be when the other sheep / great crowd were identified as having hope on earth.
Another example of how Watchtower are rewriting their own history.
The text in the OP is not incorrect, it just doesn't tell the whole story. The Russell teaching was that the earth would be populated by resurrected non-Christians. Christians were in heaven (in two groups), the rest of humanity on the earth.
Though Rutherford was wrong on many counts, this is something he got right because Jesus had used "Kingdom of heavens" and "Kingdom of God" interchangeably. (Mathew 5:3, 5; 19:23, 24)
Zion's Watch Tower, August 1884, page 7, article "Parable of the Sheep and Goats"
(Note: it was not until 1935. "other sheep" become equal "great crowd". Before that those were separate classes: "other sheep" earthly class and "great crowd" secondary heavenly class.)