Well, here's something to complicate the question: there are many takes on the King's Great Matter that emphasize Henry's quest for a son in explaining his abandonment of KoA for Anne Boleyn. And certainly these explanations have in their favor the singularly important piece of evidence that the one queen who never had her marriage cut short (so to speak) by Henry one way or the other was the one who died of natural causes, Jane Seymour, who was also the mother of Edward VI.
But against this account we can posit that KoA was by the late 1520s a short, somewhat pudgy middle-aged woman whose preoccupations were religion and charitable pursuits, and Anne Boleyn a fetching, witty girl who had never shared his elder brother's bed.
I think it's
possible that Katherine could have the son and there still be some kind of horrifying marital breakdown, perhaps aggravated by the very idea that with Katherine having produced the heir, everyone takes for granted that Henry could not replace her (because if there has ever been a human being who chafed at the idea of not being able to have his way, it was Henry VIII).
So, returning to the thesis of the original post, I think it's two separate questions whether Katherine produces an heir and whether she stays married to Henry until the end.
One other thing we perhaps shouldn't take for granted is that no Henrician Reformation means no English Protestantism. With figures like Wyclif in England's past, and others like Cranmer and Tyndal in England's present, it seems likely that there is going to be some kind of insurgent movement even if there's no open break with Rome. The dynamics might even be somewhat like what the Stuarts went through in the seventeenth century, or the French Wars of Religion.
IOTL Henry VIII and his first wife, Catherine of Aragon, were unable to have a surviving son, which of course led Henry to want to divorce Catherine and remarry, and then to start the English reformation when the Pope wouldn't grant an annullment.
So, what if Catherine had had a son, and she and Henry stayed happily married until the end of their days? Would England still turn Protestant at some later point? If not, what kind of alliance would be most likely (England-France vs the Hapsburgs? England-Spain vs. France?)