To be honest I think it's just a matter of making a good game. Once the game is accepted as being good people don't care about the payment method anymore. The reason why all of a sudden people enjoyed F2P is that they got ripped off by many MMOs in the last couple of years with sub fee, and there is nothing worse than paying money monthly for a crap service!
Like I mentioned before, crappy sub based game have had a resurgence by moving to F2P because those people who did not want to pay for a generally crappy experience can now play the small parts of their game which are decent without paying a penny.
Thus, if Carbine release this game bugless, with good leveling and a challenging endgame then they could make a payment method based on a "give us your mother for a day" and nerds would still jump in!

:bananasex: