I am yet to see anyone have a big, bold forecast at this subject. Not that I actually want house prices to fall - quite the reverse - but I would like to see a stronger debate about it (and have some other bugger do the necessary research to support the debate). I am concerned that all stories are either predicting a "small fall" or "no growth for a while" or "there's room for further rises".
Productivity actually fell in the last quarter of last year, gross wages have risen, but net wages have not - so I'm not sure how sustainable increases are, unless these factors improve. There is an air of unreality about the housing market right now.