Don`t forget that this will be a niche game... same as is EVE which is now running strong since ?9-10? ( with sub payment ) years, one time payments will not keep the servers running and the Devs paid forever.
Cosmetic shop is limited ( if you dont add pay2win in it ), as a paintjob for your cannons or sails is not really something that gets the masses hyped.
NA is not a game that will bring in the masses of 12-18 year old super nerds that spend big bucks from moms CC on fast paced games like Planetside 2. Just check the thread with the average age of the NA players and you will see that Game Labs will be better off with a payment model that aims for the "mature" gamers with an income that can fund a monthly subscription to get their relief from the days in the office.