I think Installer will end up being the 'spring board' for developers into the App Store. Either the Installer Developers will be able to raise enough money from being listed in Installer. . .and then they can apply for the App Store.
I feel Installer will still strive(though not as much as the App Store) but as an outlet for open source applications. Since Apple still charges 99 dollars a year to be listed. . .a completely free/open source path is not available via the App Store.