Quite a few add-on authors say the direct opposite, that an WebExtensions only future will kill their add-ons and that there is no way mozilla will be able to provide enough APIs to stop that from happening.
PS: It goes without saying that Giorgio and NoScript due to their popularity and because Giorgio is very well networked within mozilla get a lot of special treatment an add-on that has only a couple of hundred or thousand users will not. This isn't a bad thing, for NoScript at least, but does not help other add-on developers.
Some examples:
- https://github.com/hultmann/multifox
- http://www.chrisfinke.com/2015/08/21/my-future-of-developing...
- http://www.downthemall.net/the-likely-end-of-downthemall/
PS: It goes without saying that Giorgio and NoScript due to their popularity and because Giorgio is very well networked within mozilla get a lot of special treatment an add-on that has only a couple of hundred or thousand users will not. This isn't a bad thing, for NoScript at least, but does not help other add-on developers.