FYI - Chapter 11 is a protection against that happening. A good many Ch 11 filings are simply to re-structure debt, especially in today's economy where financing is more difficult to come by.
Debt is not the issue here, but the protection against simply cancelling is in place, as with any BK filing.
If assets remain once it's all said and done, they also cannot just say...oh, let's just cancel these and issue new ones. It's just not done that way if assets remain after bondholders and preferred are satisfied.