I've asked the AWS MP folks to enable as many instance types in as many
regions as possible. I am also pushing a new imageset across all regions
this coming Monday, which would include all updates upto 31st Aug 2016
applied in already.
No sign of a new image and the existing "
CentOS 6 (x86_64) - with Updates HVM
" still doesn't support c4-8xlarge. Can you confirm this is still in process?