Winston, purified, is supposedly filled with "ourselves" - meaning the desires and wishes of the Inner Party. He drinks, he gets up late, he hangs out in Chestnut Tree Cafe, he has a sinecure. He meets Julia and their meeting is awkward, punctuated by a lack of emotion, and precisely the inner hardness and separation that O Brien wanted and that Winston sought to escape from before the moment he first wrote in his diary.
In fact it is not quite the same, for Winston is now no longer aware of that isolation. He drinks heavily and he plays chess, and he worries about the news. His anxious thoughts are gone, but whether O Brien's confident statement that never again would Winston be capable of "ordinary human feeling" is correct is debateable. Take the drinking. He drinks heavily, freely, just like Jones, Aaronson and Rutherford, and countless others while waiting to be re-arrested and executed. But why the drink? If you were full of the Party following Room 101 there would be no need. Is Winston trying to hide something from himself - disgust? anxiety? Julia? Is he completely capable of those thoughts but merely repressing them? That is not quite what the Party wanted, of course. But the prevalence of “synthetic gin” in Oceanic society suggests that this is another area, like prostitution, where the Party knows that is ideology cannot sustain itself in purity for long – because humanity has not been crushed, not been stamped on, only repressed, and will survive. Sex is necessary, alcohol essential to hide the experiences, to fill the emptiness of the Party (and it is, “fear, rage triumph and self abasement”) an emptiness, just like it is in real life.
O Brien highlighted "fear, rage, triumph and self-abasement." He mentioned love of Big Brother and loyalty to the Party - but "everything else we shall destroy - everything."
From the final lines of the book, which contrast with an earlier segment, before he was arrested, Winston, in the bliss of the news of military triumph, imagines the "longed for bullet entering his brain" - he delights in this vision, this fantasy of his own death, "his soul white as snow".
With his tears of love for BB and his joy at the news, together with his conquest of the "false memory" that comes to him there of a happy moment of his childhood, Winston has been hollowed out. O Brien has his wish, and Winston finally belongs to the Party.
And so he wants to die: because the Party want him to die, because they have engineered him to desire death at the point of his "perfection" - which is now, the very end. It is a reaction to his self-discoveries here: there is no self. Only the internalised Party and that, as intimated here and throughout the book, is a kind of living death. But O Brien does not look or sound dead, you might argue. No, but then he is a power-mad loony (c Private Eye), and so his type, as we have seen for the last million odd years, flourish in societies which destroy normal human beings.
Incidentally, the final point of the novel is made: the love of the Party is death. The theme of the novel has been "thoughtcrime is death" - as a totalitarian warning; but now we learn that it is this evil and hollow Party that is death. It is a re-statement of the vital values of civilisation and freedom. As readers we knew this already, as Winston used to know - but the point is made with the self-sacrifice of the hero, who gives up, finally, any hero status he had, even in the physical act of survival (which was intended and controlled by the Party of course) - and is scooped out, once and for all.
There is nothing left to do except fulfil the dream, which, we must imagine, would take place at any point of the Party's choosing following this moment.