I poked around some. You've probably seen these pages, but I'll post them anyway:

a. [This page will interest you][1].  It includes a photocopy of a letter from Elo himself stating the possibility:  

 > Thus over time the rating scale could drift unless some measures are taken to stabilize it.

He further mentions that the ratings scale has no anchor, no fixed point. Compare to an athlete who runs a race in an hour; an hour now is the same as an hour 50 years ago.  *Time* is such a fixed point.

b. Also, hasn't the 'inflation' question already been answered by recent revelations of high ratings coming out of isolated areas?  [See the "Pool of Players" section of this page][2] for an allusion to the issue.   [Additional support][3], though it is not scholarly nor particularly informative. Search for "isol".

c. The [Elo wiki article][4] talks about inflation as if it's an accepted fact.  

d. Here's a [germane article about inflation][5], and [the followup][6].  Look at that smoking gun in 1986!


  [1]: http://www.chesshistory.com/winter/extra/ratingstitles.html
  [2]: http://www.kaggle.com/c/ChessRatings2/data
  [3]: http://www.chessforums.org/general-chess-discussion/11013-evile-ratings.html
  [4]: http://en.wikipedia.org/wiki/Elo_rating_system#Ratings_inflation_and_deflation
  [5]: http://members.shaw.ca/redwards1/
  [6]: http://members.shaw.ca/redwards1/update.html