Honestly, I'm against talent trees, per say. I don't like the idea that if I complete one tree, and I'm heavily restricted in the other trees, I get screwed when one of those other trees ends up being "necessarily in the eyes of the players" in order to do some content. This sorta spats in the face of what FFXI had going for it, which is the ability to change sub, gear, and such to really change your characters capabilities, while still being the same role.
I would prefer something like a single, large talent tree for each base class. ordering the abilities by theme, old up the right, warrior up the left, while still being able to reach across to the other side any time you have an adjacent ability.
I'd keep the allocation points for abilities and traits, to limit abilities, but making some abilities cost more.
Then have multiple levels of each ability, not as in cure 1 and cure 2, though they both would still exist, along with cure 3 and 4, but as in level 1 of cure 1 would give access to the spell to the native class, for instance conjurer. then cure 1 level 2 would reduce the amount of allocation points that cure 1 costs for conjurer. Cure 1 level 3 would give cure 1 used by conjurer AOE capability and allow the other classes have access to cure 1 level 1.
Each level of an ability would augment the ability itself in different ways, keeping in mind that the native class would get more augments, while others would be a few steps behind. Some levels of an ability(this is the first time I typed "ability" in this message and didn't have to correct the spelling) would lower the allocation point cost of the ability/spell/trait.
Abilities, weapon skills, spells and traits would all be treated similar, with an occasional one being native class only.
The abilities/ws's/traits/spells that would be native only, would be the most effective of them, and likely be the staples, such as Dragoon's Jump, Sentinel from FFXI's Paladin, Frost/Flare/Quake for the black mage..
There would also be unique pieces of gear, exclusive to their respective class that would improve certain abilities, which would further cement uniqueness.
I would also like to see something similar to class mods, kinda like in borderlands(yes....borderlands) that would be achieved through allocating certain abilities.
For instance, most abilities would have a modify number attached to them, that's only applied to the respective class, so say "cure" would have "pld 5", "Defense bonus" would have "pld 2", Sentinel would have "pld 5". now these do nothing in and of themselves, but when those total points equal to a set number on the respective class, in this case Gla, the gladiator then becomes a paladin, and along with it comes a few small bonuses native to paladin such as a trait that radically improves shield performance, a trait that improves enmity generation, and maybe an ability that "focus the pld's magic ability in his shield" that temporally reduces damage taken from all enemies in front of him.
Of course there would be more than pld for gladiator(every class would be more than one) such as Soldier (a Warrior type DD that uses Buster swords, such a better name that "great" sword) and Mystic Knight (kinda FFXIV's RDM, which would have enspells, minor support spells, minor debuff spells, all elemental based, and specializes in long swords.)
If the character had enough class mod points to become more than one at the same time, they would become the class that had the higher number of points, and if they were even, well, there's a few options for that one.
This would correct the issue that I mentioned in the first paragraph, and would still have a good deal of customization. It would bring in many of the classic FF jobs, while still keep the number of individual classes to a smaller number making it easier to customize, and easier to keep them unique.
Whatever the game becomes, I really hope they don't go with something moronically simple, or just do what they're doing over at rift or WOW with slight mods.