I was telling my wife that within 20 years Google will be much like the movies we see of the future. The computer will be a centralized appliance in the house that we can interact with from any room. We'll interact with it by talking to it. We'll ask Google "Who was that modern artist that painted swimming pools?" and it will return "David Hockney" in an expectedly pleasing female voice (or male, depending on your settings). "Would you like to read a biography of David Hockney?"
My wife asks, "Will it make your food for you?"
"No, it won't make your food. Not in 20 years."
"It'll also say 'Save 20% on a biography of David Hockney on Amazon.com. Would you like to receive a quote for painting services? Buy a swimming pool today, get it installed next week! Take art lessons from home.'"
Well, yeah. That's a good point. As Google transitions into new mediums, so will the ads. But i'm optimistic—I think the future holds less intrusiveness, or at least not any more than we have now. Ads will continue to become more targeted so what we hear will become more relevant and interesting to us. If they become too intrusive, we'll go elsewhere or alter the services we consume—in general we'll have more options and more power over the prominence of advertising in our lives.
When we experience intrusiveness in advertising currently, it's caused by a power imbalance between consumer and the advertiser, which is caused by lock-in and monopolies. Lock-in across many industries are beginning to unravel. Intangible goods delivered digitally, and services that are quickly and inexpensively duplicated, are becoming more difficult to keep locked in. Music, movies and books are easy to transfer to others (legally or otherwise). Independent labels are beginning to challenge the major labels. Blogs are beginning to challenge the mainstream media. VoIP is challenging the telecoms. All of these things are shifting the balance of power towards the consumer, and allowing us to dictate the terms of the agreement.
This doesn't mean that those in power aren't struggling to keep the balance the same. The RIAA and MPAA are struggling to lock down music and movies, to cripple all viewing and listening devices. The telecoms want to cripple the internet for those that can't pay. Patent laws are crippling innovation by competitors. Trademark laws are attempting to exert unreasonable control over basic language use. Those that would attempt to shift the power away from the individual belong in the Hall of Villainy.
Fortunately, the genie has left the bottle. I don't know how long it will take the villains to realize, but they are not getting it back.