So the way this will work is that at level 10, you will pick one of your class talent trees in which to specialise. The other two will be locked out to you until you have either spent 31 talent points in your primary tree or bought dual spec. When you pick your primary talent tree, you will also get some extra abilities which are associated with that tree.
For example, Protection Warriors get Shield Slam, Vitality (improved stamina) and Vengeance (the stacking damage ability which is common to all tank specs). That means that no non-Protection warriors can ever have Shield Slam, as opposed to now where it’s a baseline skill. Similarly, only Fury warriors can dual wield and only Arms warriors get 2H weapon specialization. So if you want to dps as a protection warrior, you’ll need to do it via sword and shield.
So none of this is finalised yet but I think it’s the clearest picture that we’ve had yet of where the devs plan to go. And it’s somewhere that, “An Arms warrior can throw on a shield and tank an instance,” has no place. It’s also somewhere that you’ll get some of the most iconic abilities for your talent tree as soon as you pick it, rather than at much much higher level.
That at least is a boon. But less so when it means the other specs lose a baseline ability to make it happen.
This mostly affects levelling. It has been fairly common up until now for players to level in a dps spec and still find themselves well able to tank/heal levelling instances. I remember healing a lot of instances while levelling my druid as feral, for example.
That may change. It’s difficult to know yet if there is still the intention to let players heal/tank as offspecs while levelling. But if not, expect longer waits on the LFG. Although many players who intend to play healers will happily accept slower levelling speeds in order to have their healing spec, far far more will decide to just learn to heal later on and go for the fast levelling instead.
And alternatively, there may also be plans to bring down the cost of dual spec (a long long overdue change) and make it available at a lower level.