when the developers involved with Selenium suddenly decide to just drop a browser for one of their sub-projects then this might very well indicate a trend - even if it's just that firefox is less actively supported in future.
I understand where your concern is coming from, but I think you're missing a few of the pieces:
* When it comes to Selenium, Simon (the guy you replied to) is about as authoritative a voice as they come.
* The death of Selenium IDE is anything but sudden. It's really been more of a zombie for years and just kept kicking along. It's been saved from absolute death a few times over by generous support of volunteers willing to pick it up. But I don't think anyone tracking Selenium development is going to be surprised by this move.
* Selenium has been on a multi-year quest to shift support for the browser drivers out to the browser vendors by way of the WebDriver W3C standard [1]. The goal is for Selenium to be more of an interface to browser-specific implementations of the WebDriver specification more than anything else. Which is to say, Selenium dropping support for a particular browser shouldn't be too concerning because the major browser vendors will be maintaining their own driver implementation.
* Slightly related to the above point, but Selenium IDE is not and never has been maintained by Mozilla. The Firefox WebDriver implementation, however, is. And Mozilla is heavily involved in the editing and drafting of the WebDriver specification.
when the developers involved with Selenium suddenly decide to just drop a browser for one of their sub-projects then this might very well indicate a trend - even if it's just that firefox is less actively supported in future.