What happens is someone with money buys out the deal for pennies on the dollar or there is a successful renegotiation with lenders or there is a successful renegotiation with the limited partners (in the US most real-estate deals are structured as limited partnerships with the general partner as an LLC).

Basically, except in the first scenario everyone agrees to suffer together. In the first scenario, the initial investors suffer and the new investors think they got a good deal. It's worth noting that LP's are usually built from people who have worked together before or from people with track records of being good to work with.