Ok, I want to make it clear that I don't expect all of these in the PHB. And that I'm willing to compromise on them for the sake of certain D&Disms. But I have long believed that one of the great strengths of D&D is that any character archetype you can visualize, you can create. It might be a D&D-ized version of that archetype, I'm fine with that, but it will be that archetype. Now, strictly speaking, this has never been completely realized, but its come close. Still, there are certain holes that I'd like filled.
I think that all of these should be valid combat character archetypes. Bear in mind that I'm speaking generally- if I say "sword," and you want "ax," that's fine. And I don't think that the class for all of these archetypes needs to be "fighter." It can be whatever, as long as it genuinely does the job.
Sword, shield, heavy armor. Your knight archetype. Looks like fighters and paladin cover this.
Sword, shield, lighter armor. Realistically, people don't spend all day in heavy armor. Its heavy. Warlords seem to cover this, I think. So does cleric.
Two handed sword, no shield, heavy armor. Fighters, paladin handle this.
Two handed sword, light armor. Barbarian covers this in 3e, maybe it will in 4e?
Two handed sword, no armor. Your wandering ronin type. I can accept adding light armor as a D&Dism. This has not typically been a supported character archetype. It should be.
Heavy armor, polearm. Fighter.
Light armor, polearm. Think Jackie Chan with a broom or a ladder. Was a fighter in 3e, kind of. You could get the spring attack, attacks of opportunity, and so on, but the skills weren't correct.
Two swords, heavy armor. In 3e this was the samurai.
Two swords, light armor. Probably ranger in 4e. Was ranger and rogue in 3e.
Sword and dagger, light armor. This is not the same as two swords. In 3e, this was a poor choice, because the shortsword was better than the dagger, and because you were making it harder to use weapon feats. The difference between this and "two swords" is that the dagger is somewhat defensive, whereas "two swords" implies offensive use.
Dagger and one empty hand, light armor, tendency to cut people's throats from behind. Rogue covers this.
Sword and one empty hand, masterful duelist. This is your "My name is Inigo Montoya!" character. Its not clear whether this will be supported any time soon in 4e. It wasn't particularly well supported in 3e, until the lackluster swashbuckler class.
There are probably more, but I think that all of these should be possible. I don't think they all need their own class. I'm ok with them being blended together. I just think that for any one of these, if a player says "I want to play THIS," it should be possible, and not suck.