Thinking about it, I think the Austen adaptation I would like to see / read was one that combined Pride and Prejudice with King Lear.
Rich but arrogant bachelor (Darcy / Lear) has choice between marrying three sisters. Proposes marriage to the one he likes best (Elizabeth / Cordelia), but she turns him down because he acts too proud. So he then goes and marries the other sister (Kitty / Goneril) but of course, she's only marrying him for his money and soon divorces him (claiming half his property in the process), only to marry his arch-rival (Wickham / Edmund) - a man who bears our hero an old grudge and dreams of usurping his power.
Stung by this treachery, Darcy asks after Elizabeth again, but hears rumours that she's gone off and married Mr. Collins and moved to France. Miserable and bitter, Darcy is left vulnerable, and easily seduced by Lydia / Regan (who, of course, has been having an affair with Wickham all along). This marriage proves short-lived as well and Darcy, heartbroken, deprived of three quarters of his fortune and out of favour with his aunt, turns to drink and gambling, eventually ending up in the poorhouse from where he is rescued by the ever faithful Bingley (Edgar).
In the meantime, Jane (Gloucester), makes a spirited attempt to protest Lydia's treatment of Darcy, whereupon Lydia blinds her with a hatpin, leaving Bingley with two invalids to take care of.
Eventually, Elizabeth returns and Darcy begs for her forgiveness, but it turns out she's only returned from France because she's dying of consumption. Her death drives Darcy mad and he commits suicide. Meanwhile, Bingley, distraught at the violence done his wife and by Wickham's usurpation of Pemberley, challenges him to a duel and kills him. Kitty and Lydia are left destitute (Pemberley having reverted to Darcy's aunt given that Wickham had no male heir) and join a nunnery. The book ends with Mr. Bennet (Albany) standing alone in his garden delivering a mournful speech.
There, that's what I call an adaptation.
Opening line: It is a truth universally acknowledged, that a single man in possession of a good fortune is to God as a fly to wanton boys.