Why doesn’t she simply write a new will or do a codicil to the original one? Does she no longer have mental capacity?
As she has no assets and the estate is insolvent, why does she need a will? It would then just be dealt with under the terms of intestacy.
If no one does anything about it, the whole matter gets left in abeyance. To be honest, with an insolvent estate, it’s not uncommon. If the property is in negative equity, it would just get repossessed and sold. It depends whether it is in negative equity or not.