Neat Graphic [MENTION=92511]steeldragons[/MENTION], but I almost feel obligated to ask: to what purpose?
For a class to be a subclass of a core class, it has to share some common features. Lets just look at the current "Fighter" subclasses in your graphic.
A Fighter gets 3 attacks, d10 HD, All Weapons and Armor, and combat maneuvers.
A Barbarian gets 2 attacks, d12 HD, All Weapons but no heavy armor, and rage mechanics.
A Ranger gets 2 attacks, d10 HD, All Weapons and but no heavy armor, Spells, and Favored Enemy mechanics.
A Paladin gets 2 attacks, d10 HD, All Weapons and Armor, spells, and Holy Powers/Oaths.
A Monk gets 2 attacks, d8 HD, Limited Weapons, No Armor, and UNarmed/Ki abilities.
What, exactly, links these classes together aside from the fact they hit things with weapons? Not a whole lot. Different proficiencies, HD, abilities, and attacks. At least in the mage -> Wizard/sorcerer/warlock/psion area, they have the same HD, same weapons/armor, same class abilities etc. There is even less overlap between Cleric/Druid and Rogue/Bard; aside from some legacy issues, there is no need for these classes to silo back into the core four.
UNLESS
You plan on wildly gutting them to fit nicely into the skin of their parent class. For example, getting rid of paladin/ranger spells and giving them 3 attacks, or making monk and barbarian d10 HD classes. Likewise, if you're going to druids into just a Nature domain variant cleric (with shapechange their channel divinity) then I see little value in this.
Really, its just a burning desire to categorize everything. To say make Druids, Barbarians, and Bards into Clerics, Fighters, and Rogues of a different stripe. To be honest, I could even see Sorcerer and Warlock stand on their own as well. However, I cannot fathom the rationale to try and cram the other six classes into the remaining three classes.