AdWords, Google & it's partners will become saturated for every popular search term.
Yahoo & eventually MSN (if they can ever get there act together and keep the greed under control) will remain secondary players.
If you look at the Over/Yahoo forum you will read about many of the problems they are facing already.
Google content sites will become more important then ever.
We are both AdWords advertisers and AdSense publishers and the feedback I am getting from our local businesses that are showing up on my sites is very positive.
Google needs to keep the quality of the content network high by being aggressive in the policing and fair with it's advertisers and publishers. So far my experience has been positive.
The third tier PPC companies will remain that. They do not have the quality partners or the will to police their programs to provide any consistent ROI.
We have tried a total of 4 third level PPC providers and it was just a money hole. The shills for these companies will now jump in and say you can work the system and get a decent ROI but who has the time for such small results.
There will be others who for various reasons will not want to hand the crown to G however the reality is that for the foreseeable future I see no other result.