I would think that RE4 would make some additional sales its first holiday also. Especially if Capcom is going to PUSH for 2M PS2 sales, that advertising will raise awareness to those who may have missed RE4. I know quite a few people who only buy games in the holiday season, so a quality game like RE4, the limited GCN selection, and the PS2 advertising push for the port could add a nice little holiday spike.
Another possibility is RE4 could win the Game of the Year award for the GCN if Zelda dissappoints much. If that happens (unlikely of course) the added exposure could add a spike in sales.
Of course I never made any predictions and wont knock anyone elses. I personally did not have high hopes for this title. I was shocked at the reviews and shocked at the sales all things considered.