Well from just the looks of the artist renditions the most unique airworthiness considerations appear to be blade loss and birds.
The blade loss is more than just containment, it also considers imbalance and mount loads as well as windmill issues.
Forget about those big blades and birds and look to the core engine itself for any issues on bird ingestion..
It seems to me that the blade containment issue can be addressed at the aircraft level under it's minimization rule with a little bit of shielding and moving stuff out of harms way (don't ask about today's props
