My prediction is that Google's algorithms for working out what clicks are worthy and what clicks are close to useless will improve, widening the eCPM gap between sites with high quality traffic and those whose visitors are ad blind and/or don't have much disposable income.
Good and Bad things goes hand to hand As we can see now adsense has more ppc competitors and after changing adsense ad style clicks has been decreased for those publishers who have low traffic also earnings are less . As far as my opinion concerns i think google will rich soon and surely they will have more publishers more advertisers but the revenue for publishers will go down and down. Few ppl who r new in this field they will find adsense as a GOD blessing coz they r earning from this prog.
I think, "Earning" will be the concern that webmasters will stay off Adsense. Again the problems are always there like: they had already banned thousands of Publishers accounts without proper reason, Their earning per click / Click through rates are decrasing day-by-day. So.... Keep your Fingers Crossed
Not for all niches. Some niches will get better income but just like in every business, there must be up and down. Many niches will lose its potential, that's for sure.
It doesn't really have something to do with adsense itself, but i hope the worth of the US Dollar will rise, because it really make's a difference. 1 Dollar = .69 Euro now. That's the lowest it has been last years, and it seems it will get lower.
Earnings may be little more than this year due to more people coming online (more advertisers, more visitors) but eCPM surely going to fall even further. Google is going to get a lot of "investors" pressure which will even make further cut from the pie. Google has already tried many other ways to use its advertising service (like referrals, mobile ads, video ads), but none of them picking up. I am not even expecting them to be picking up any time further. People know that Google make more percentage cut from the amount what advertisers pay. It is easily evident from the referrals where you can compare the prices at google referrals and other places. So publishers are hardly going to use them untill they show what they cut. Only hope for google (in investors point of view) now is to buyout more and more sites where they can keep the publishing revenue as well as advertising revenue. To be frank, I don't have very high hopes with google for 2008.