It would be the biggest non-surprise in the world to hear industry players say that spam and virus attacks will get worse. It's slightly more of a surprise, but still not shocking, to hear estimates from anti-spam professionals that spam will also get more clever. Postini, a company acquired by Google not long ago, is one of the world's largest anti-spam vendors. According to them, fighting spam is only going to become more difficult as spammers begin to actively try and work around spam filters.
Some of it we are no doubt familiar with. Messages with in-line images rather than any text, for instance, which make parsing the message difficult and the message itself more dangerous. They also cite spammers taking more advantage of holidays or special events, such as the Olympics. Even more devious, and something we have seen malware writers begin doing as well, is the specific targeting of certain companies or even certain people. None of it is surprising, but it's still quite interesting. You can download and read a full report on how they expect the dominion of spam to change in the next year.