Hmmm thinking about the php7 stuff would it be possible to make a plugin that scans and tests plugins and theme and then list all that are incompatible? I mean that would help both people wanting to change to php7 and plugin and theme author quickly test their own. I mean I know the other way would be cloning your site and testing but this would make it that little bit easier plus if it outputs the errors people can even copy them to support channels to make it easier.

This is just an idea for someone who might actually be able to create this and wants to help get more people moving over to php7.

Or maybe this already exists and I just don't know about it.