have ignored the firefox add-on world these past few months and looking in, don't see any major new developments?
(it could also be that the new addons.mozilla.org is bad at surfacing relevant content)
in any case tab mix plus finally released a webextension. it only has the features of a v0.1 though
http://tabmixplus.org/forum/viewtopic.php?f=8&t=19974
i am still waiting anxiously for a real powerful tab management solution a la Tab Groups. things like that and TMP are hobbled by the lack of new FF APIs they'd need to implement their old features, though. it will likely be a while before this situation improves much.
@gcupc yeah. i haven't checked bugzilla recently, just know that they're nebulously "in the works"
@gcupc hey, speak of the devil. good news:
https://www.reddit.com/r/firefox/comments/7rhlnl/tabgroups_the_tab_hiding_api_is_completed_and_it/
way sooner than i expected. there is also a fork of the upcoming replacement add-on that is already functional (i didn't test)
https://www.reddit.com/r/firefox/comments/7vdzqj/i_made_a_tab_groups_replacement/
@alyx There's plans for tab-hiding APIs that will improve things like Tree-Style Tabs. I gather that they're not out yet because of security concerns.