The info comes from a comment in the BlueStacks support forum where BlueStacks employee Deepak Sharma said that the team is "considering offering BlueStacks for Windows R/T (sic) next year." If this works out, it would allow users to run any of the 700,000 Android apps on a Windows RT tablet.
But, that's a very big if. Given the restrictions that Microsoft has placed on Windows RT apps, it seems highly unlikely that a BlueStacks app would be allowed on Windows RT. Of course, Windows 8 for tablets is expected to launch in January, so at least BlueStacks will already be available for use on those tablets through the legacy support.