Here's why I think bringing BB10 to the PB before launch date will be an excellent marketing
We all are excited and full of joy because of the launch of BB10 on January and the lucky ones that have a Dev Alpha A/B or even the C, can already demonstrate to their friends what BB10 can do and make them to try the new OS. But the ones who don't any BB10 devices, can't show BB10 in the same way, and are mostly limited to show YouTube videos and official demos and they can't easily leave a good impresion. Therefore, if RIM update the PB to have BB10 before January 30th, the BlackBerry People that don't have a BB10 device can then show to the esceptical the great power of BB10