ScenicViewer - I agree with your reasoning. However, there is only so long the Society can continue exploiting "flipping" as a source of income. For example, no matter how luxurious the new HQ in Warwick turns out to be, it will never yield the same value as the Brooklyn HQ properties combined - they're just too valuable thanks to their location.
Once they're sold, the most lucrative asset in the Society's portfolio will have been liquidated. If donations eventually dry up completely (or down to a trickle), and they become solely reliant on property transactions, they will eventually run out of properties to sell (or "flip"). That's why I think it's likely that the Warwick site is actually intended as the final "bunker". Either that, or Patterson, with its many hilltop properties away from the main complex (where the Society's doctors and lawyers currently live, to my knowledge). They could sell off the main buildings, and retreat to a gated residence on top of some hill that could serve as their compound.
Just a few thoughts...