You're absolutely right Non-anointed faithful JW's who die before Armageddon are relegated to the status of "other sheep." You're also correct that this doctrine is becoming more significant as time passes.
The question that the JW leadership must answer though is whether this group exists by quirk of fate or by divine intent. In other words, are these simply prospective members of the "great crowd" who had the misfortune of dying too soon, or do they formally comprise a third distinct class of Christians in JW theology?
The two class JW system is based almost entirely based on Revelation 7. There just isn't a third group to work with.
Jesus’ disciples entertain one of two hopes. First, a "little flock" numbering 144,000 has been gathered—anointed Christians of both Jewish and Gentile backgrounds who are "the Israel of God" and have the hope of ruling with Jesus in his heavenly Kingdom. (Luke 12:32; Galatians 6:16; Revelation 14:1) Second, in the last days, "a great crowd" of "other sheep" have manifested themselves. These have the hope of living forever on a paradise earth. (Isaiah's Prophecy II pp. 241-242)
First, Jesus gathers an anointed "little flock" who become joint heirs with him in the Kingdom of the heavens. (Luke 12:32) After this, "a great crowd" are gathered to survive "the great tribulation," coming out of it to inherit everlasting life in the realm of God’s Kingdom on earth.—Revelation 7:9, 14-17. (The Watchtower January 1, 1995 p.4)
They also discerned that the Bible holds out two destinies—a heavenly one for the 144,000 anointed footstep followers of Christ and a paradise earth for an unnumbered "great crowd" of "other sheep." (Revelation 7:9; 14:1; John 10:16) (The Watchtower May 15, 1995 p.18)
Therefore during the Christian era, the other sheep and great crowd are for all practical purposes, synonomous:
Finally, in 1935 the other sheep living during the time of the end of this system of things were recognized as being the great crowd seen in vision by the apostle John. (Isaiah's Prophecy II p. 255)
But on May 31, 1935, in a discourse given at a convention of Jehovah’s Witnesses in Washington, D.C., U.S.A., it was Scripturally explained that the "great crowd" ("great multitude," King James Version)refers to the "other sheep" who live during the time of the end. (The Watchtower February 15, 2003 p. 19)
Those of the other sheep gathered in the time of the end will make up the "great crowd" destined to survive "the great tribulation," with the prospect of living forever on a paradise earth. (The Watchtower February 1, 2002 p.21)
In a stirring talk on "The Great Multitude," delivered to about 20,000 conventioners, J. F. Rutherford presented Scriptural proof that the modern-day "other sheep" are identical with that "great crowd" of Revelation 7:9. (John 10:16) (The Watchtower May 15, 2001 p. 15)
Who are marked on the forehead by that "man"? "Other sheep," ones who have the hope of living eternally on a paradise earth. (John 10:16; Psalm 37:29) In 1935 this group of "other sheep" were discerned to be the "great crowd . . . out of all nations" seen in vision by the apostle John. (Revelation 7:9-14) (The Watchtower January 1, 2000 p. 12)
I already mentioned the problem of Christian salvation. A faithful Christian whose destiny is no different that those that lived before Christ is a contradiction in terms. This cuts to the heart of Christianity and what is allegedly the immediate benefit of the ransom. If the JW's were to teach that the earthly hope has always been an option for Christians it would create a group of Christians who do not attain to one of the two salvations depicted in Revelation 7.
Currently in JW theology, only two groups of Christians attain a righteous standing:
To whom does this righteous standing come? First, to his anointed followers. Because they exercise faith in Jesus’ sacrifice, Jehovah declares them righteous with a view to adopting them as sons and making them joint heirs with Jesus. (Romans 5:19; 8:16, 17) Then, "a great crowd" of "other sheep" exercise faith in Jesus’ shed blood and enjoy a righteous standing with a view to being friends of God and survivors of Armageddon.—Revelation 7:9; 16:14, 16; John 10:16; James 2:23, 25. (Isaiah's Prophecy II p. 211)
Notice that first comes the cleansing, then the blessings. This has proved true in our day. Back in 1919 the anointed remnant humbly submitted to being refined, and Jehovah "washed away" their uncleanness. Since then, "a great crowd" of other sheep have also allowed themselves to be cleansed by Jehovah. (Revelation 7:9) Thus cleansed, the remnant and their companions have been blessed—Jehovah has taken them into his protective care (Isaiah's Prophecy I pp. 71-72)
And the immediate benefits of the ransom applies to only these two groups:
Paul also explains that this reconciliation involves two distinct groups of individuals, namely, "the things in the heavens" and "the things upon the earth." (Colossians 1:19, 20; Ephesians 1:10) That first group consists of 144,000 Christians who are given the hope of serving as heavenly priests and ruling as kings over the earth with Christ Jesus. (Revelation 5:9, 10; 7:4; 14:1-3) Through them, the benefits of the ransom will gradually be applied to obedient mankind over a period of a thousand years.—1 Corinthians 15:24-26; Revelation 20:6; 21:3, 4. "The things upon the earth" are those individuals in line to enjoy perfect life in Paradise on earth. Revelation 7:9-17 describes them as "a great crowd" who will survive the coming "great tribulation." (Draw Close To Jehovah p. 146)
Would anointed Christians be the only ones to enjoy the blessings promised to Abraham? No, for Jesus’ sacrifice benefits the whole world. (1 John 2:2) In time, Jehovah revealed that an unnumbered "great crowd" would survive the end of Satan’s system (Draw Close To Jehovah p. 197)
And only these two groups render "sacred service" in the "spiritual temple"
Since the first century C.E., Jehovah’s temple has actually been a spiritual one, with its holy of holies in the heavens and with a spiritual courtyard on earth, in which the anointed brothers of Jesus, the High Priest, serve. From the 1930’s onward, the "great crowd" have worshiped in association with the anointed remnant and are therefore said to serve ‘in God’s temple.’ (Pay Attention To Daniel's Prophecy p. 267)
With consciences cleansed, anointed Christians render "sacred service to the living God." And so do the great crowd. Having cleansed their consciences through "the blood of the Lamb," they are in God’s great spiritual temple, "rendering him sacred service day and night."—Revelation 7:14, 15. (The Watchtower February 1, 1998 p. 21)
Besides theological problems, there would be a considerable loss of face for the JW leadership. The current JW concept of an earthly class of Christians was kicked off with a clear and unambiguous identification of the great crowd:
Especially beginning in 1935, when the identity of the "great multitude," or "great crowd," was clearly understood, large numbers of these began to manifest themselves. At first there were hundreds, then thousands, later hundreds of thousands, and now there are millions spread around the globe. God’s infallible Word depicts this group as ‘coming out of the great tribulation,’ being survivors of it, living right on into God’s New Order without ever having to die. (Revelation 7:9, 10, 14; John 11:26) The early members of this group are now in their 60’s or 70’s or older. Jehovah did not allow the ingathering of this group to begin too soon. The "great crowd," including many of the earliest members thereof, will survive into the "new earth." (Survival p. 185)
The JW's have gushed over this and called it a "bright flash of light" more times than I can remember. If there has always been a class of Christians with an earthly hope, this entire episode would not only look silly, it would require that the alleged history leading up to the 1935 convention (e.g. The manifestation of the Jonadabs, as something new in the history of Christianity, their reluctance to accept consecration etc.) be rewritten and forgotten.
I don't want to sell the JW leadership short when it comes to wiggling out of a tight spot, but at the same time, they need to come up with something extremely clever here.