The Second Circuit is usually not shy to certify unclear questions of New York law to the New York State Court of Appeals. But in Dalton v. Harleyville Worcester Mutual Ins. Co.
it declined to do so. The definition of what constitutes a "collapse" of a building had not been decided by the Court of Appeals, and the Second and Third Departments of the Appellate Division have taken different views. Rather than certifying the question to the Court of Appeals, the Court decided that the term was ambiguous and should be resolved against the insurer.
I would anticipate a motion for rehearing, asking that the issue be certified. The case involved the all too common occurrence of an insurance company disclaiming liability for damage that appears to be covered by the policy. Perhaps that is the reason that the Court acted as it did. The decision can be found here