Yes, and for numerous reasons there was a dramatic increase in Dem registration in 2008. That will not simply vanish this year, although it will be reduced for sure.
This is an opinion I am not arguing with you... But based on feel, garnered in part from reading the enthusiasm numbers and part being aware of how many millions have left the Ds, I predict R will turnout in even or higher numbers than Dems. Its part of the reason I have been saying Romney is winning this whole time.