the personalisation goal has always been fundamentally flawed. Its based on the supposition that when you enter a conversation with another human you gain a benefit from being aware of the person and there background and this places you in a better position to reply. However when i want an authorative answer it normally means asking that question to someone who i personally have identified as being well placed to have the information/answer i require. They will often know nothing about me at all. For example many people will go to a conference to hear google employees talk and answer questions on their relevant subject. Its the audience that have the benefit of knowing the google employees and their personal background and not the other way round. In other words personalisation really means users picking a search engine of choice and not the engines knowing all about the person asking the question. The search engine needs to concentrate on providing information and the user will need to ask the right question. This is in actual fact the way it works out in the human world.
The holy grail is infact asking the question to the right person. So your most likely to get the right answer if you ask the question to someone authorative than asking the question to your next door neighbour who knows every detail of your life.