estate with no assets

My dad died 6 months ago in Alberta, Canada. His will names his two eldest (of three) children as executors. Neither is willing to act in this capacity. He died with no assets, lived in a rental retirement suite, nothing of value left. He left 2 insurance policies with named beneficiaries which have been paid out. He has a couple of small unsecured debts (<$10,000). His final income tax return has not been filed, appears he owes the government $1100. His cremation expenses have been paid. What happens if nothing further is done, i.e. no one steps forward to complete the role of executor? His children are in agreement that there are no assets, nothing to squabble about. The will provided for the equal distribution of assets between the three children - no assets, no problem.