There was a post a few days ago that drew a comment from Arnie Perlstein who has devoted a lot of time and effort to uncovering a secret subtext in Jane Austen. He has a blog on the subject if it interests you. I've only skimmed it so far but it looks interesting enough to me.
What do I think?
I am quite certain there is all sorts of subtext in Austen. In fact, I think you'd have to be crazy to think otherwise. Look at the playfulness of Northanger Abbey and you see a writer who was probably constitutionally incapable of resisting the temptation to litter her writing with all sorts of sly allusions and in jokes for her family and friends. (Fanny Price's name, for example, could well be a rather rude pun as some writers have suggested.)
BUT and this is a huge but, there is a giant difference between having subtextual elements and having a consistent secret subtext and I don't think there is a such a subtext running through Austen.
The most obvious reason, to my mind, for thinking so, is that the novels are so good. A novel or poem with a single subtext running through it is a dual purpose thing. It's like one of those cars that is also function as a boat. What you get is a pretty crappy car and a pretty crappy boat. It works but not nearly so well as a car that is just a car or a boat that is just a boat.
The first hint that a work may have a single subtext running through it is that it creaks a bit when you try and read it as straight text and that is most emphatically not true of the Austen novels. Austen wrote these books to be read as texts.
That will no doubt be a disappoint for some people but really, read the text. As readers we can convince ourselves that we are being terribly clever rooting out bits of subtext but for writers, the ability to put everything right on the surface is often more impressive. There are very few writers as good at it as Austen and there are no other novelists as good.