I had an idea. It sounds like a lot of work, will need some balance but here it is anyway. It's intent is to introduce more diversity but make it easier to balance and add some flavor to gameplay.
Anet introduces new F2P specializations called Focused Specializations. These specializations may only be active when its counterpart is active. See the example:
Lava Specialization (new) can only be activated if Fire Specialization is already active.
Ice Specialization (new) can only be activated if Water Specialization is active.
Insight Specialization (new) can only be activated if Inspiration Specialization is active.
Enigma Specialization (new) can only be activated if Chaos Specialization is active...
...and so forth.
All classes will have Focused Specs for each core spec, so 5 per class. However, it's up to Anet. 3 Focused Specs per class works too.
Balance: I think this makes it easier for Anet to balance classes. If a Focused Spec breaks something, just nerf the Focused Spec. You see, having a Focused Spec guarantees that you can only have 1 other unrelated spec (say, running Arcane Specialization while having Lava and Fire active) which limits how much synergy the Focused Spec can utilize.
^- In other words, it should be easier to balance Focused Specs since there is less potential (broken) trait synergy. Plus, Focused Specs are always balanced around the prerequisite spec.
That's pretty much it! What are your thoughts?
(There will still be 3 specializations per character)