I’ve been reading a lot (img below). So. The following… “predictions”, in NO WAY, could be wrong: 

Those Focus talents seen on Specs: Companions only – the Inquisitor’s specs will likely share the talents but in a different layout with only 3 actives. I’m rolling with that for now. Why???
- Those Focus spells chosen for the Companions are a way of personalizing them – as we’ve talked before, it was not out of the table that a skill or two would differ to better suit their personality, preferred fighting styles and backgrounds: notice how Hail of Arrows while not the best fit for Artificer, it –screams- VARRIC. Expect the same for all other Companions, it’s not *necessarily* about the spec, but the character who has it (which IMO is very cool).
- On that note: just because you see Stonefist and Fire Storm on SOLAS’s Rift Mage spec, that doesn’t make it “another elemental tree”, that makes it Fire Storm is Solas’s Focus talent. Rift Mage is still very much what it says on the description; expect Force, physics, crushing-based. Forget Earth about “Stonefist” (if that’s still its name). That’s matter being conjured out of the Fade to be hurled at foes to crush (shatter! & other detonating effects) and knock them back.
- I’ve considered other possibilities. As many pointed out, Redcliffe Quizzy had both Stonefist and Haste. Plus: We’ve seen Viv casting Firestorm more than once (which breaks the pattern, that’d be Solas’s Focus unless we’re getting repeats). But anyhow. These couple other theories make less sense to me, mostly because they take away the ID factor for Companions – they have their stories & have had many battles, it stands to reason that, i.e Varric, regardless of being this more gadgeteer kinda Rogue (Artificer as spec); his FOCUS, his special ability, what differs him, would lie in Archery (Bianca!). The Inquisitor, on the other hand, is our character to make.
- The Inquisitor: has Mark of the Rift (confirmed a Focus talent) & that’s gotta go somewhere, and that somewhere is probably where we’ll find the other (all 4 of them for each class – for a total of 5 with MotR) for us to choose from (can't wrap my head around Focus being forced into the Inquisitor's spec, when it's not pre-determined, acquired at different points in the story + where would Mark of the Rift fit into this? So... O.o). I also believe Mark of the Rift will be our 1st (free!) Focus Talent and presented early-esque in the game, too; to introduce us to the mechanics of Focus (like, a tutorial of sorts) and so we can plan ahead how we’d like to build our Inquisitors.