I think, too that there's a good chance that Google will collect enough data to improve their algorithm's beyond link authority.

Actually, Ive thought about this quite a lot..for example if I had some great link bait tool or something like that which I could give away to other sites including a link to my site..I would think twice about it and wonder whether the benefit of the additional links that might give me, would really outweigh the future benefit I could get from people actually staying on my site to use the tool.

But dead in the near future? I think that is a pretty bold statement :-).

I think it's going to be a slow/gradual process that will take quite some time. However I think usage data is prone to being spammed, too and that they might be looking rather to use usage data to improve their algorithm by having a strong second ranking factor.

Maybe it will eventually be more important than linkage data, we'll see - maybe once I get out of college people will ask on SEO forums: how can I get my users to stay on my site??? How can I make them come back??? instead of "How can I get links?" "I need link bait!!!" :-)