As mentioned above, this has little to do with AWS and more to do with keeping our cloud platform up to date. At some point we do have to stop supporting older versions. If you are running custom items you have had developed, you really should be accounting for the fact that these will have to be kept up to date alongside the platform.
It needs to be noted that there have been 12 releases, including one feature release, and even a security related release since 4.5. Whether we were updating our infrastructure or otherwise, you really should be thinking about upgrading.