Not in the next 5 years I can't see much changing. Only PPC spend becoming bigger which is music to Google's ears.
In my opinion SEO will be needed as long as search engines live, which does not necessarily last forever.
I went to an interesting conference on a subject similar to this a few weeks ago. As a matter of fact budget spend online is actually still increasing at a faster and faster rate. Large companies are now launching some of their products solely online or online first. Advertising revenue for television and radio is dropping. Sooner or later TV advertising revenues will be critical due to the a larger proportion of the mass market spending longer online than watching TV and reading publications. New technology such as Sky Plus that alows viewers to skip the adverts make traditional TV advertising almost redundant. However the online marketing industry is also set to change. With the advent of Web 2.0, online communities and social computing advertisers will be forced to spread their spend over a larger number of mediums. SEO will still be important as long as people use search engines, though this may change focus as providors strive to deliver personalised results to users. Companies will improve the useability and community feel of their sites. Things such as corporate blogs and podcasting will become more commonplace and companies try to 'connect' with their customers. These are exciting times, the growth in online media is increasing and the playing field is continually changing as peoples internet useage patterns change. Traditional SEO's mill be forced to adapt to their customers requirements of a broader online presence.