TO be honest, the broadness and fact that you can take a Champion Fighter and make them ANYthing, works just fine for me. EVERY class needed one of those. A "general, simple, non-specific default" of the class. The fact this was an Evoker Wizard and a Thief Rogue are really open to debate. But a Champion Fighter fills the bill beautifully.
Then add other subclasses that get more specific or add complexity or narrow [to a point] in concept. So, other than the fact that "Battle Master" really does mean nothing, and the term warlord carried waaay too much baggage, I think the Fighter worked great.
Champion = generic default
Battlemaster = added mechanic complexity
Eldritch knight = added mechanic complexity and story/narrative restrictions/specific assumptions [in this case, learning/having access to arcane magic]
I would have much preferred a "generalist Wizard" default. A "basic" thief-Rogue default. And I suppose "general/pantheon-wide or cause/alignment-specific" cleric. Specifying into Domains.
BUT, we gotta works with what we gots.
[EDIT to add] So basically,what we should see in the case of additional subclasses coming out, would [to my mind] be something like this...
Cavalier: goes in the "Battlemaster" tier. Their shtick is basically they do mounted better [


]. Different Mechanic complexity. Something like a "Brawler" as a subclass, would fall here also. The class complexity/differentiation is mechanically based. No explicit or implied story or narrative assumptions need be made about these guys. You can make characters of a fairly wide diversity with just their mechanics making them different from other subclasses.
Things like: Warlord, Gladiator, Knight would be en par with the Eldritch Knight. They have/need both mechanics and story/flavor assumptions to make them different enough to warrant their creation instead of just playing a champion with feats/skills/backgrounds that can give you a "gladiator" character or a battlemaster + feats/skills/backgrounds that give you a "warlord." Those options are still completely valid and available for players, but to make these concepts a subclass of their own, they need the mechanics and the flavor specificity to, for me, justify their existence.
At the same time, I would very much like bloat to be avoided. So just because someone can come up with a synonym for "warrior" that has a slightly different connotation or mechanic speciality, is not, to me, a "good enough" reason to make it a subclass.
Does any of this make sense or am I just talking out my arse/making things more complicated than they needs be?