It's kind of funny how the low budget Swedish film adaptations of these books pretty much had zero problems being made compared to the big budget Hollywood versions.
The Swedish versions, however, come off as extremely low budget. The American remake of the first novel was very well done.
If they do write out the Blomkvist character in Girl Who Played with Fire, you lose his entire storyline. The two characters don't even meet in the novel until the final chapter. It would need to be re-told in some other fashion, as it is critical to the plot. Not impossible, but exceptionally difficult.