Then you have a problem with how much do you charge. And how much money do the publishers and developers get. It's unlikely that 15 USD a month will be enough. I find it doubtful that even 50 USD a month would be enough. Would consumers be willing to pay 100-200 USD a month?
And that still doesn't address how much companies would get from that. You can't just split it equally. If you did, companies would no longer have any incentive to spend the money to develope something like KZ2, Halo: Reach, GTA4, etc. Base it on time played and some of the smaller developers might get even less money now than they do with the current system.
Which then goes back to how much do you charge each month? Publishers would no longer have the ability to rely on blockbuster sales to fund new IP which might or might not have a positive ROI.
Eventually you'd end up with a system where you'd have mostly PopCap style games. Being a PC gamer, I love this myself, as it would encourage AAA Publishers and Developers to abandon consoles and go back to being PC only.
But that certainly doesn't help the PS3.
Regards,
SB