PS2 on PS3, how might it work?

According to an interview with GamePro, SCE's Hardware Marketing Director John Kohler mentions that Sony is "absolutely interested" in providing downloadable Playstation 2 games, which would be similar to the Xbox Originals downloads available on Xbox Live. Of course, Playstation 2 games would have to be emulated on all newer PS3 consoles, since those newer models no longer contain internal legacy hardware to run said PS2 games.

This brings up the following questions:
-If Sony were to go through with such an endeavour, would the emulation software be coded into the firmware of the Playstation 3 or will the games themselves be reworked on an individual basis to run on the PS3?
-If the emulation software for PS2 games is coded into the Playstation 3 firmware, will it allow the newer PS3 consoles to run PS2 disks, or will consumers be forced to re-purchase the games that they may already own through the PS3 online store?

None of this is certain yet as it is unclear whether or how actively Sony will pursue downloadable Playstation 2 games, but should it happen, I really don't want to be forced to download a copy of Shadow of the Colossus when I have a perfectly good copy sitting in my stack of games.


Source: GamePro (relevent information on second page)