Even though Google doesn't owe us publishers/affiliates anything, they still have developed loyalty with us through programs like AdSense. If they took over the SERPS completely with knol and made the info-sites irrelevant, that just seems like a bad business move to me on many levels.
Keep in mind, even though people see AdSense as Google giving away some of their revenue to us, the bottom line is AdSense is a profitable program for them just like AdWords. So getting rid of affiliate/information sites would mean a huge decrease in AdSense payouts and that would slow down the amount of advertising dollars pumped into AdWords - the
real Google money-maker.
Anyway, I'm babbling....and as you said, it's in the early stages so we'll have to see what happens. I still have my faith in Google... for now.

Knol could have some impact, but I just can't see it wiping out affiliate/info sites altogether in the SERPS. At least that's what I'm going to tell myself for now.
