Will Firefox and Pale Moon work together in the future?
Since Mozilla has obviously chosen to follow a different path at the management level, it doesn't seem likely that Pale Moon and Firefox will ever see a unification or joining of forces.
Mike Beltzner (Product Director for Mozilla Firefox) did get in touch, but the contact was rather brief, limited to him asking about the baseline optimization of Pale Moon and asking to discuss the main coding differences, but it was made clear that Firefox was not going to cut away the essential things needed for the kind of optimization done in Pale Moon. With the way the query was put and the lack of further responses after explaining the basic optimization being done in the build process and not by changing code, it feels rather like Mozilla was looking for a quick fix/source code snippets to address some issues Firefox seems to have, rather than a sincere offer for cooperation. I'm therefore also less inclined to take future approaches seriously.
In addition, there have been conflicts of interests between Pale Moon and Firefox as far as the so-called UX (User eXperience) developments are concerned. This results in a different user interface approach in Pale Moon. For example, less stress is put on minimizing the size of UI elements or saving every pixel possible to benefit the content area - in this day and age of full HD monitors and laptops that seems to be very counter-intuitive.
On the flipside, some developers seem to complain that Pale Moon "is no different than other optimized builds out there" (meaning other people who have built Firefox from source on Windows machines) - which might be true; in the end, though, it is still the past experience to strike the balance needed for a general browser that can be used not just by tweakers or developers but by everyone that counts. Following the step-by-step instructions in the Mozilla Developer Center, and probably with some trial and error, anyone with a decent level of computer knowledge could build Firefox on Windows (if you have the right hardware and software), but that doesn't necessarily mean it's going to be stable or efficient.
Some have even claimed that the Pale Moon project as such was given shape to gain fame -- they should consider that the popularity was unexpected. Pale Moon is, and has always been, released in the hope that it might be useful to its users, nothing more. It takes up a good chunk of my free time (between developing/building, releasing, website maintenance, and providing all e-mail support myself), and I'm happy to see it finding good use among its users.