I'm not sure how likely this is. Whilst they won't want to be lumbered with a half(+) empty buidling if they do finish it off but can't sell the flats, on the other hand I would have thought they would have taken a few reservations and would want or even be obliged to finish the building and hand over these flats?

However they will no doubt have done the maths as to how much it would cost to finish versus how much it will cost to sit empty, and it may be that they can just refund the deposits and mothball. Apparently people are now (generally, not specifically here) starting to walk from new homes and leave their deposits...