I think Elizabeth Bennett married Darcy for his house.
So do I! When she visited Pemberley, and thought "Hell's teeth! What a pile! All this could have been MINE!" (Minor paraphrasing here, as cannot recall Austen's actual words
) - she suddenly sees him in a different light.
I think Lydia Bennett and Wickham will pretty soon have fallen out of favour with each other - I'd give it six months. They are both too selfish, and she's too flirtatious - once he loses interest in her she'll be shagging Denny and any other officer she can get her hands on.
Mr Collins is an idiot, but Charlotte Lucas knew what she was taking on, and as someone else has said, made her own space in the relationship (though how she managed to bite her tongue with Lady Thingy, I don't know). I think the Collinses will have been fine. He's too stupid to see what she thinks of him intellectually, and she's to clever to let him know.
Marianne Dashwood was effectively sold to the highest bidder, and I think will have run off with the raggle-taggle gypsies-o within three hideous years - and Colonel Brandon, who is besotted with her because she is the image of his lost love, will get fed up with her, too, and be miserable before the honeymoon's over.
Fanny Price's life after wedlock doesn't bear thinking about - they are a creepy bunch in that family.
Elinor and Edward Ferrars will be happy, and will Jane Bennet and Bingley (possibly two of the most uninteresting and wishy-washy characters in the history of literature - I doubt that they will even be able to pick names for their children.)
Emma and Mr Knoghtley - mmm - I've never been too comfortable with his mildly paedophiliac tendencies. He'll mould her into the image he wants if she will let him. Either way, one of them will be disappointed.
I think Captain Wentworth and Anne will be happy enough together - they've both learned a lot over the years, and know what they are letting themselves in for.
The female I have most hope for is Margaret Dashwood - Elinor and Marianne's younger sister. It is my fervent hope that she never marries anyone, but becomes and explorer and travelling the globe by camel. She is such a free spirit that marriage would destroy her - she must bestow her favours where she will - on ebony-skinned African nobles and flinty-eyed Mongol warriors; on dashing Cossacks and exotic Bedouin princes with liquid eyes and cruel cheekbones; on proud Samurai knights and tawny Indian chiefs; on gorgeous men of her own choosing as and when she wishes (please God - don't let her settle for an English banker or a Dutch tulip magnate).
If that girl doesn't shag her way round the world on behalf of us all, I shall be sorely disappointed in her.