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That is a very interesting statement. I'd always considered the development team, the art team, the sound team, the old lady that makes the coffee and crumpets, their office rental, power bills and all the CS staff and whatnot a reasonably large part of the production cost.
Count up expected staffing level, salaries and double that for overhead costs and related and work out what you expect the monthly cost to be. How many F2P purchases do you need to cover that and how many subscriptions?
I'm glad I'm not in that business
Out of curiosity, what do you consider a good F2P model for a game?