Well, I think this excellent novel has a lot that it can offer the modern audience. Certainly there are a number of themes such as marriage and courtship and the role of women in society that are very interesting, but for a more modern audience to whom the restrictions of womanhood at the time of the novel may not seem so relevant, perhaps the overwhelming theme that may be interesting is the theme of the power of imagination and how it can blind and distort our judgment.
Emma of course is a perfect example of this, as she is so fixated on matching Harriet to Mr. Elton that she is blind of his own attachment to her--something that even the reader understands before Emma does. After the shocking revelation, she reflects on her thoughts and concludes that she had "taken up the idea, she supposed,and made everything bend to it." Of course, the irony is that whilst Emma is just trying to place Harriet and Mr. Elton together, Mr. Elton construes her actions as offering him encouragement.
However, let us remember that it is not Emma alone who suffers from this. Mr. Knightley has an automatic bias against Frank Churchill because of his relations with Emma. Emma again is rude about Jane because of her envy of Jane's fine accomplishments. When Harriet feels drawn to Knightley, Emma's fervent imagination creates a relationship between Harriet and Frank to help disguise this fact from herself. Likewise, Frank uses Emma as a screen, and he believed that Emma was aware of the reality of the situation between him and Jane.
Throughout the novel, the skill of Austen in reporting these many events allows us as the reader to see the mistakes and errors of the characters before they do themselves, and the plot gives each character a series of epiphanies which allow them to understand how their judgement was influenced by their feelings. Perhaps the most important quotation from the novel, coming after the happy ending, explores this theme of mistaken perceptions:
Seldom, very seldom does complete truth belong to any human disclosure; seldom can it happen that something is not a little disguised, or a little mistaken; but where, as in this case, though the conduct is mistaken, the feelings are not, it may not be very material.
As Austen puts it, mistakes are always going to be made, but as long as we are sincer in our emotions, these mistakes can be overcome. This is an important theme that has massive relevance to us today, and indeed, is a timeless theme of this great novel.