Give Core Professions Attention
They kind of already do…… but the Core specs, by intent, are not focused the way Especs are. There are still a lot of strong builds that only use Core Specs, but harder content (Fractals/Raids) specifically benefit from the greater utility focus of most Especs.
Honestly they don’t need new mechanics, its more that each core class has a blind spot in their setup (by design) in order to push group cohesion. What the HOT Especs did was fill those blind spots with a highly focused build theme, giving them very satisfying, and much needed build diversity.
If anything needs to be tweaked, its that some core specs have obvious best in slot choices, largely due to that class having poor internal synergy. I’m looking at you Ranger.