This is the first time this has come up that I'm aware of. Since you actually get the original contract and number, I would assume that the banked week would go with it to the new owner. Just realize that this is actually a week banked with II and is no longer points. They are not retrievable and you could use them only for an exchange through II. You cannot exchange back into DVC with this week. Once you're closed, get a search going and keep your fingers crossed. If you need suggestions or help with this issue, I'd be glad to offer a hand as I'm sure others on the board would also.
You will have around 250 properties available within II, they are listed in the member guidebook. There may be an occasional addition or subtraction along the way and MS exchange department would be able to help. Prominent suggestions would be any one of a number of FL or SC Marriott units, especially summer for HH and winter (school allowing) for south FL. Also consider HI, Cancun Royals, Aruba and Grand Cayman. I can also offer insight into the specifics of many of the resorts. Let me know the exact expiration date, unit size and season deposited and I can make further suggestions.