It seems to me spam is going to evolve in two different directions, and both are going to be very interesting. On the one hand, we're going to have chat robots that will try and engage you in realistic-looking conversations...though ultimately it will turn out that they're trying to sell something. Yet this will be no different from making a "friend" and ultimately finding out that the reason they were being nice to you is because they want you to buy candles they made. That kind of sucks, but it's a problem as old as time...and as long as you're enjoying the conversation in the meantime, who cares?
On the other end of the spectrum, we'll have the logical extension of "chock hedgehog" with machines that are consistently generating content that mechanistic filters cannot differentiate from intelligent communication. I enjoy chatting with xpaerimtlslaekv...who for all I know is merely a "spam"-generating robot that's gotten aggressively good at remixing web content through algorithms in order to generate mutated work that looks like the product of a complicated mind. When confronted with fascinating art, why worry about how it was made?
The Robot Liberation Movement is well underway, and it's important for us to remember that in a very real holistic sense...We Are the Robots!! (as Kraftwerk has duly pointed out).
On a related note, this comic is Totally Awesome.