With GCM 3 it is possible to send notifications to iOS devices, using GCM,

This means a new variant type needs to be created on UPS, containing all infos from both: GCM and APNs. UPS would just speak with GCM, while that one takes care of APNs mapping. This is nice, as GCM has nice features, such as topics, device-groups, that make sending to GCM cheap, compared to APNs.