I don’t think it will be that extreme. More of the benefit will come from Google recognizing which definition of a term you are looking for so they can send you to the right sites. For example if I search for the term “surf” frequently, they will see I go to sites about surfing waves in the ocean and not surfing the web.
So if I type in surf faster, they will probably pull up tips articles about surfing from professional surfers rather than the current top 10 for that term which are all landing pages for internet providers.
Now some sites like say PokerListings are going to have a lot of people visit them for a wide range of poker terms. So they will probably rank high for everything, but lets be honest, they already do.
Either way, search history is a history, so for any new users, you will still have the same chance of ranking high. It will just be more important than ever to rank high for a few long tail keywords, so you get logged in someones history and later if they search other more general terms, you have a chance at ranking.