<<Is it not already illegal to strip DRM in the US? Do you think it has affected the amount of ebooks sold? >>
As people discover that it is easier to remove DRM from epub than Kindle, I think you will find as more people become savvy, they will buy epub. It will be hard to determine though - the market for Kindles will change because Walmart and Target are no longer selling them.
As far as illegal vs. legal downloads, I have to tend to agree with the poster who thinks more will illegally download since doing EITHER ONE would be illegal. If the cops seized your computer or iphone due to an unrelated crime, could they then charge you when they discover all your DRM removed files?