As the magic 8 ball says: "Cannot predict now".
The reality is that we don't know yet what is going to be required to continue to run non-WebExtensions based add-ons past the release of Firefox 57. All we know is that Mozilla has stated that for Firefox 57:
- Firefox will only run WebExtensions.
- AMO will continue to support listing and updating legacy add-ons after the release of 57 in order to have an easier transition. The exact cut-off time for this support hasn’t been determined yet.
It had previously been stated that the restriction to WebExtensions-only would only apply to the Release and Beta channels, so:
It may be possible to continue to run non-WebExtension based add-ons on:
It is currently unclear if these will actually be possibilities. If they will be possibilities, it is unclear for how long it will remain possible for older add-ons to function (both due to changes to Firefox and/or non-WebExtensions being intentionally disabled). The fact that AMO will continue to support listing and updates to non-WebExtension add-ons is an encouraging sign that we will still be able to use them in Firefox releases that are not the main Release and Beta channels.
Other options include:
- The Firefox ESR 52 release. The pattern is that this would be supported through the normal release of Firefox 60, or so. Personally, I feel that Mozilla should plan to have an ESR release prior to any major changes in functionality (i.e. have a Firefox 56 ESR), but that does not appear to be how Mozilla does things.
- The various forks that have been made of Firefox. Each fork would have to be checked to see what their plans are for this change.
- Any new fork made specifically to continue to support non-WebExtension add-ons.
- A hack may be determined to re-enable non-WebExtension support, similar to the one that exists to disable checking for add-on signing.
You should keep in mind that the plans are for Firefox to fundamentally change in the future. A significant reason for moving away from the more capable add-on types (non-WebExtensions based extensions along with complete-themes) is to allow Firefox to be changed without the need to consider maintaining compatibility with more capable add-ons which rely on the internals of Firefox for their operation. When, exactly, these breaking changes will be rolled out is unclear.
Personally, I'm in a similar boat. None of my released add-ons are possible to move to WebExtensions. Many of the other add-ons which I use are clearly not possible to move to WebExtensions. Frankly, I'm not looking forward to using Firefox without the capabilities some of those add-ons provide. Thus, I will be continuing to look at what options are available as we get closer to Firefox 57.
However, even if I find no option to use more capable add-ons after Firefox 52 ESR is EOL'ed, I may continue to use Firefox. My primary reason for doing so instead of switching to Chrome would be the fact that Firefox extensions go through a review process, whereas Chrome extensions released though the Chrome store can be very bad from the point of view of both security and privacy.
