Dana
You make a great point around the various facets of SEO and how long term some may be affected. However, I think there will be a need for SEO going forward just as there was after keyword meta tags and seeing how many times you could get the keyword in faded. I remember about ten years ago a gentleman came and presented to our company about eZines and how they were going to revolutionize the web, etc. Obviously, they did have an effect just as the PRWebs/newsline, etc. (web trash I affectionately call it now) have an effect today. But, will they still be here tomorrow? Don't think so, IMO.
There seems to be a continuum that goes one side to the next. This is driven not in a small part by those who think of the search "system" as something to beat. So, black hat says use a link wheel, hide links in periods and colons, etc. But, my belief is that people who search will ultimately determine what is Optimum or not. 5 years ago I was looking for a water pump for a small fountain for my home in Houston. I searched on Fountain pumps etc. + Houston and could not find anyone with a fountain pump in Houston. tons in Ohio, etc. I have now watched as the web has become more and more localized. That was driven not by the engines, but by their customers.
Remember that with Panda or Penguin, many perceive it as Google spanking a bad child and I see that as not being thought through. Google understands that when I search for water pump Houston and someone or two or 5 have gamed the system in order to show up high on page one, but none are in Houston. That is not a good result for GOOGLE. There customer does not like it because they were clear about what they wanted. So, the technical SEO will be there as it is very important. But, good content that is not stolen, spun, or rehashed by a "PR" vomit machine is what people want and what they will come back to over and over. If I know I can search on any engine and consitently get what I was looking for, that is where I am going.
Remember, this is a change but one that will allow the early adopters and true believers to gain a lot of real estate if they are diligent.
Thanks so much for your thoughtful responses,
Robert