What is the function of the lack of resolution in 1984?
1984 has a resolution, but it is not a pleasing one. Instead, the state crushes the individual, and there is little hope that the future will be any different.
Remember, 1984 is a comedy--a political satire. The focus of comedy is usually on the society--its ills, evils, and illegitimacies. The function of a comedy's resolution, of course, is for these to be remedied by the end--and to have some laughs along the way. Neither of these happen in 1984: Winston is tortured and rendered an unperson. There is no Big Brother or Goldstein or the Golden Country or revolution or love or memory. Only room 101. Rats. A boot heel crushing a skull. Pain. Suffering.
The resolution is not even pleasing as a tragedy. There is no tragic hero--no heroism at all, in fact. There is no tragic flaw--no course of action that Winston could have taken to avoid his fate. He was being set up, like us the reader, to be tortured all along. Sure, we had hope that Julia or Goldstein or the revolution could gain traction. But, in the end, we were duped, just like Winston. The bitter laugh is on us.
The resolution, I think, is the novel's brilliance. Hundreds of years from now, 1984 will be remembered, along with the fiction of Aleksandr Solzhenisyn, as the most brutal accounts of the atrocities against the individual perpetrated in the 20th Century. For those victims of totalitarian governments, there is only torture, death, and fatalism. Hope and love were non-existent for two or three generations. Orwell characterizes humanity at its believable worst.
The ending should be no surprise for those in the USSR or Nazi Germany or Fascist Italy. Only we in democracies are surprised by the how effective the gruesome and lethal machinery of government, technology, and hate can destroy a people and their will. But, Orwell is there to remind us that it can happen in Britain and in the states.