Mearls laid out the standard that for WotC, the standard is about ten possible Subclasses at minimum (not that all the PHB Classes are there yet).
Could the Psion have 10 sub-classes? Well, there have been more than a few psionic classes and sub-classes over the editions.
Psionicist
1)Wild Talent
2)Psion
3)Psychic Warrior
4)Soul Knife
5)Wilder
6)Ardent
7)Battlemind
...
even Monk. ;P
And, in 4e, at least, there were builds under each class, as well, the Psion, for instance, could be a
8) Telepath,
9) Telekinetic, or
10) Shaper
sadly the builds for the Ardent and Battlemind weren't quite so differentiating.
Sounds doable. And, like you said, 5 years in, they haven't even gotten to 10 ea for all the PH classes, even given all the MC-like builds cross-pollenating among them.
Warlord
official builds:
1) Tactical
2) Inspiring
3) Bravura
4) Resourceful
5) Skirmisher
6) Insightful
plus an alternate feature that substantially changed the class if you took it:
7)Archer Warlord
Then there was a fan build that received official support
8) 'Lazy' Warlord
And, there were Paragon Paths, quite a few, but two of which suggested to me ideas for the kind of MC-lite archetypes the fighter and rogue both seem to get:
9) Arcane Battlemaster (name lifted from a Paragon Path): In the D&D world, spells very often turn the tide of battle, if not decide it from the beginning, so it only makes sense that there are commanders who shape their tactics around the effective use of caster assets, and, probably, pick up wizardry second-hand, INT-focused as the warlord can be.
10) Infernal Strategist (ditto): Some will pay any price for victory. The Infernal Strategist employs both magical powers and diabolical gambits gleaned from the darkest and most perilous of arcane sources.
Two more ideas along those lines:
Crusader: The 1/3rd Cleric or half-Paladin Warlord, a leader of zealots and champion of a divine cause, who, in the D&D world, obviously can't get away with it without displaying actual divine powers.
The Thaneborn (name lifted from barbarian build): A traditional leader of a clan or tribe or the like, by right of birth. The Thane leads 'his people' in battle, and others call those people 'barbarians'). A faux-Barbarian-MC who's rage is not as potent, but is 'contagious' to his allies.
And, general brainstorming has seen additional ideas like:
The Hector: Originally suggested by Wrecan based on a small number of Warlord exploits that it could be built around, but clearly under-developed in 4e as it tended to encroach on the Controller role, for obvious reasons.
This is the warlord who harangues, taunts, deceives, and outmaneuvers the enemy into making tactical mistakes and generally playing into his hands. The Hector focuses on his enemies more than his allies - allies, you should be able to count on. The Hector's acid words are carefully chosen and wickedly delivered to goad enemies into the worst course of action before them. You might think that such tactics are worthless against enemies who speak a different language or that lack the capacity for thought at all. But, humanoids have many forms of expression in common besides words, and it takes only a passing knowledge of a culture to know what could set someone off. And 'mindless' enemies are the easiest of all to manipulate, as they are the most predictable of opponents.
Protector: Protectors are capable individuals who take responsibility for the welfare of others. Anywhere there's even a trace of civilization, people need to be guided and protected, often from eachother. Protectors may work from a position of legitimate authority, like a peace officer or sheriff, they may be chosen by acclaim, looked to naturally in times of trouble, or even be self-appointed would-be heroes. They make a point of guiding, keeping save, and, when necessary, saving others. They will also tend to be adept at defusing potentially violent situations or resolving them with limited injury and loss of life. They emphasize prudence, common sense, community spirit and organization. Even when working with very capable even reckless allies like adventurers, the Protector counsels caution and careful, deliberate action - but, very often, Protectors do not heed their own advice, and may dash in to play the hero in moments of crisis.
The Artillerist: Whether actual medieval siege weapons, archers, or casters provide it, the advantage of a stand-off capability cannot be overstated. Setting up and making the most of that advantage is the specialty of this Warlord. Where there are not source resource to direct, the Artillerist takes up whatever weapons are available to provide the direct advantages of ranged support to his allies - taking a shot at just the right moment, even if it is easily dodged or blocked, can give an ally an advantage or opening, or put an enemy out of it's best tactical position as it seeks over or crouches behind its shield...
The Marshal: This is the Warlord who, by whatever means, 'marshals' lesser troops - volunteers, conscripts, villagers, bandits, whatever - into an effective fighting force. It's a classic trope, 'training the villagers to fight for themselves' for instance, and, it side-steps one of the problems with attack-granting and barking commands: this Warlord doesn't have to do it with PCs, mussing their precious bad-boy doesn't-work-well-with-others edginess. He has his own NPC grunts to abuse. It also side-steps the problem with pet classes and henchmen: that they impact the action economy. The Marshal would have his unit of recruits that he commands to move around, holding positions, or making concerted attacks ("when you see the whites of their eyes!") of high value. All of which would be resolved by the player of the Marshal, on his turn, using his actions. A volley from his unit of archers, for instance, wouldn't be a bunch of attacks rolled by the DM one on each archers turn, rather, it'd be done on the Marshals' turn, and create a beaten zone, enemies in it would get skewered (save:1/2). That kinda thing. And, yes, it could include a warlord that 'marshals' animals bred & trained for combat, or a posse comitatus under the mantle of the law (or those could be broken out and be good at similar gambits)
