I know very little about SEO or website design, but isn't google already kinda tipping their hand to what the future will hold?
Without adblock, a quick google search shows that the entire top half of the result page are ads. To me, it's fairly obvious the future will bring pay-for-priority search inclusion. You want a top spot? Break out your wallet.
Whether that's a good thing or a bad thing, only time will tell. I'm more curious about search engine competitors 25 years from now. Google's had a great decade, but that can't last forever ... can it?