As with Swann, Odette herself has changed. Proust alternates between “Madame Swann” and “Odette” without a clear pattern, but it’s still evident that they represent two aspects of her, one in her role as Swann’s wife, one as the ill-bred and coarse Odette of years past. “Madame Swann” is the woman that the teenage Marcel sees, the charming mother of Gilberte, to whom he is affectionate. Odette is the person that Swann still remembers as his erstwhile love, but who no longer exists.
The “Madame Swann” of this section is defined partly by her relationship to Swann himself, but moreso by her relationship with Marcel. The Swanns initially find him distasteful, but warm to him and eventually Marcel’s relationship with Madame Swann is more intimate than that between any of the others: there is reticence and a maternal aspect to her, traits never before glimpsed. Yet the interchanging of the two names implies that there is part of the past Odette that persists, not the Odette in Swann’s mind (which is well and truly dead) but something that she envisions in herself, and something that persists in her relations with other people.
As she walks down the Avenue du Bois at the end of the section with Swann, as “established” as she ever has been and still the target of ambivalent gazes from younger men, she says to Marcel:

“You aren’t ever coming to see Gilberte again? I’m glad you make an exception of me, and are not going to drop me completely. I like seeing you, but I also liked the influence you had over my daughter. I’m sure she’s very sorry about it, too. However, I mustn’t bully you, or you’ll make up your mind at once that you never want to set eyes on me again.”
And as the average span of life, the relative longevity of our memories of poetical sensations is much greater than that of our memories of what the heart has suffered, now that the sorrows that I once felt on Gilberte’s account have long since faded and vanished, there has survived them the pleasure that I still derive from seeing myself once again strolling and talking thus with Mme Swann. (689)

(Marcel has long given up on Gilberte at this point.) Mme Swann is a different person entirely here; the years and her change in position have permitted her to participate in this experience right here, for which Marcel claims an esteemed position. It is as though this has endured even while his love for Gilberte, and Swann’s love for and jealousy over Odette, have not.
Again, the issue of taste–more specifically, of discernment–is paramount, because it’s the attunement to this sort of aesthetic appreciation, to the affecion shown within a casual social context, that Proust paints as being more enduring than the transitory passions. Thus, lack of taste towards such experiences is one of the largest failings one can have, in Proust’s world. Consequently, this moment holds a bit of redemption for Mme Swann, who, while no great intellect or moral paragon, has carved out a brief moment of bliss that has remained more strongly in Marcel’s memory than any of Swann and Odette’s unfortunate experiences. And I infer that Odette has slightly more taste too, as she can participate in such things.
It is this sort of rewriting that changes the shape of Swann’s Way in my mind, because while there was the sorrow of Swann’s waste of his life on Odette and the contrast with Marcel’s own memories of Combray, they were presented as distinct elements. Now they are intermixed and even Odette, very unsympathetic in “Swann in Love,” has facets that Swann and readers like me could not fit into the earlier framework.
That theme, if only as a subtle undercurrent, runs through the section. Swann and his wife have a relationship which has an intimacy that, if not love, is beyond sheer convenience:

As for Swann himself, she knew intimately those traits of character of which the rest of the world is ignorant and which it scoffs at, and of which only a mistress or a sister possesses the true and cherished image; and so strongly are we attached to such idiosyncrasies, even to those of them which we are most anxious to correct, that it is because a woman comes in time to acquire an indulgent, an affectionately mocking familiarity with them, such as we ourselves or our relatives have, that love affairs of long standing have something of the sweetness and strength of family affection. (505)

Actually, I’m confused as to why Proust uses the term “love affairs,” since what the Swanns have sure isn’t that. But Proust emphasizes a mysterious relation, the private aspects of what has gone on between the Swanns which are mostly not detailed, as having provided for them. They haven’t provided love, but they have provided, for Swann, stability, and for Odette, standing. And while Odette does no love Swann, nor does he bother her; there is stability there.
As Swann no longer has the demon of jealousy affecting his relationship with Mme Swann (since it’s affecting his affair with his mistress), he is in a pleasant torpor himself around her:

But so far as Odette was concerned, Swann was quite blind, not merely to these deficiencies in her education but to the general mediocrity of her intelligence. More than that; whenever Odette told a silly story Swann would sit listening to his wife with a complacency, a merriment, almost an admiration in which some vestige of desire for her must have played a part; while in the same conversation, anything subtle or even profound that he himself might say would be listened to by Odette with an habitual lack of interest, rather curtly, with impatience, and would at times be sharply contradicted. (559)

I suppose this sounds negative, but next to “Swann in Love,” it’s almost comfortable. (The reference to residual desire for Odette, however, seem to contradict what’s gone before and after, where it’s made quite clear that Swann does not love Odette any more, and so all I can say is, I give up. Such things are unknowable, if not in real life, at least in this book.) Swann has grown patient with Odette; Odette still does not understand much of what he’s talking about. But these are the ground rules, and they have provided, even still, a measure of nominal success. Swann’s ambitions have changed to fit the shape of his life, and with Gilberte around, he doesn’t even seem like the disappointed man that he ought to be.
What continuity there is to Odette is established in one cryptic passage, which draws the distinction even as it isolates a similarity. It begins with Proust discussing the importance of Mme Swann’s Garden:

There was another reason for the flowers’ having more than a merely ornamental significance in Mme Swann’s drawing-room, and this reason pertained not to the period but, in some degree, to the life that Odette had formerly led. A great courtesan such as she had been, lives largely for her lovers, that is to say at home, which means that she comes in time to live for her home. The things that one sees in the house of a “respectable” woman, things which may of course appear to her also to be of importance, are those which are in any event of the utmost importance to the courtesan. (638)

This passage is presented specifically as Marcel’s experience of his visits to the Swanns’ home, and how he feels her extend over the house so that even the flowers become an intimate particular that make him feel awkward. (Pages 638-641 or so give the full story and are very beautiful and difficult to summarize.)
But what does it mean? Is Proust taking high society down a peg by equating a woman’s dominance of her salon or other parties as similar to the control expressed by a courtesan? Is it an explanation of a continuity in Odette, detailing how she has preserved some crucial aspect of her soul after marrying Swann by removing the unacceptable aspect but preserving her sphere of influence? Does it anticipate the later quote mentioned above (page 689) by implying that the real importance to Odette’s earlier actions was not in the affairs themselves but in the aesthetics with which she conducted herself, which have developed and mutated into something not only acceptable in higher society, but aesthetically memorable?
I don’t think there’s a definite answer at hand, but there’s probably something to all three explanations. There is more of Odette in “Mme Swann at Home” than there was in “Swann in Love,” which was mostly about Swann, and if she’s not as sympathetic as Swann, she’s at least explicable and complex now.