This still has too many kinks to work out to happen in the near future anyway. You can't charge monthly, because then people will just pay for one month of the year then cancel their subscription, unless the price per month is obscene.
You could make it per year, but then you have to ensure that you have titles that everyone wants to play every year in order to justify the subscription or no one's going to bite.
The whole idea just doesn't sound financially beneficial at this point.
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i'm dumb as hell holy crap -ExThaNemesis