This was the AA problem
Incident: American B763 over Atlantic on Jul 19th 2013, cargo fire indication
I would imagine that SNN is suitable as an emergency/diversion landing for an A380. They have already carried out some take-offs and landings in SNN some time ago including during their 'round the world' road show. Admittedly not with a full pax and cargo loads. However, if the An-225 can do it with a full cargo load I'm sure it's no bother. The An-225 has been a frequent visitor to Shannon on a good number of occasions over the years. That is why I would think the runway is certainly long enough and the air steps that are available in SNN would reach the main deck doors. Would the terminal 'jet bridges' be able to manage the A380 though? I'm not sure. Anyone?
Given SNN's location it surly would be able to take an emergency or diversion of the A380.