While I understand that it would be exceedingly difficult to make games designed around the Cell work on the new hardware I think that part of MS's approach is really interesting. They use the 350 disc solely as a ticket to download and then play the game from the hard drive. I think that PSNow should adapt something like this and I think it's much more of a possibility to make a system that would allow PS3 discs to be read simply as tickets to then play said games on PSNow.
I don't expect the impossible, but I think the above is a doable solution that Sony should definitely look into.
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