ALL details of rental agreements are between the owner and the renter, and they vary all over the ballpark. It's actually almost impossible to answer your question without being the owner you are renting from, because the answer lies in the current status of their individual account.
Holding account is only one of the difficulties possible with a
DVC cancellation. Holding account happens when a reservation is cancelled within 31 days of arrival. Points in holding account cannot be banked or transferred, and they can only be used to make ressies 60 days in the future. In a worst case scenario, those limitations could render the points useless to the DVC owner.
However, there are a number of other bad things that can happen. From the time you make your reservation until the time you cancel, the account may have passed banking deadlines -- which would mean the owner would have to use the points or lose them, possibly in a very short time frame. The cancellation could put the owner right up against the end of their Use Year, which could result in all of the points being lost. And there are other possibilities.
The best way for all parties to look at a
DVC rental -- IMHO -- is that the transaction is
totally non-cancellable and non-refundable. If you take that approach, you can protect yourself the way you would with any other vacation --
trip insurance.
Renting is not for everyone. You can save a considerable amount of money, but you accept certain risks in the process. If you are not comfortable with the risks inherent in renting and trip insurance as your backup, you might be better off doing a cash ressie through Disney CRO instead of renting.