Current game development costs are around $57-80m+ for new non-indie projects, trust me, subs alone won't cover any development costs, maybe it'll pay for some of their lunches, but it'll take quite a few years time to even break even, let alone pay for it. The subs now are for the continued operation of XIV, they're even offering a discounted prices (pending) which alone should tell you it's not "to pay for 2.0".

It's to develop content (i.e patch 1.20+) and even then, making some money with your project is better than making almost zero, especially given that a lot of stores aren't restocking XIV yet in some areas.