MoonSong
Rules-lawyering drama queen but not a munchkin
Even within the martial concept, it's been used for more than that, or could be further expanded. The Bravura Warlord, for instance, was a lead-from-the-front, secondary-defender, 'Warrior' type, the Inspiring build also tended that way. Tactical Warlords, OTOH, ranged from officer types barking orders while fighting in the front line (as originally conceived) to the fan-devised (and latter expanded in Dragon) 'Lazy' (or as Garthanos called them 'Princess') builds that handed out most of their actions to other characters, either as a lead-from-the-rear commander, or as, conceptually, a non-combatant merely inspiring greater heroics in their defense.
Quite aside from the sub-class-of-multiple-classes idea (which also came up in discussions of psionics, BTW, where it was a lot more obvious because 1e psionics could be possessed by characters of any class), even a single-class design of the Warlord needs to be very flexible in the range of builds, genre archetypes, and character concepts it can handle.
(Really, any martial class does, since there are so few non-magical sub-classes, each one has to do a lot of heavy lifting. In fact, one thing that's occurred to me is that the Warlord might very well be the only non-magic-using class added to the game, possibly the first & only class to have no magic-using sub-classes, and that each of it's sub-classes could be devoted to filling some of the many non-DPR/'striker' roles currently restricted to casters. For instance, the Bravura sub-class could be a primary Defender/'tank' with only a secondary emphasis on DPR perhaps partially from enhancing ally's attacks. You could have an Inspiring (though 5e has thoroughly flogged 'Inspiration,' so maybe Icon or Paragon) sub-class that's more like the 4e-fan-devised Lazy warlord, a dedicated healer/buffer/action-granter. You could have Hector imposing conditions through taunting, intimidation, and deception or even a follower-based (phalanx, pike square, archers, sappers, whatever) Commander blurring the lines between D&D small-unit tactical skirmish game and small-unit tactical wargame, and thus tread around the ground of 'controller'/'spoiler'/'blaster' roles.)
Nice ideas, sending them to my past self so I can retroactively plagiarize them....n_n
More seriously wow, mostly the same ideas I had when I pitched to En5ider..