Fine, but none of them are going to have the training that the Assassin CLASS provides.
What does it provide? Stealth, deception (bluff and, maybe, disguise), knowing where to strike to kill, breaking in places and dealing with traps, and poison.
In one culture's legends, there were, supposedly, beautiful women (if I recall, correctly, they were noble women) trained in most if not all of these things. These women were sent to enemy generals as prizes of war and would assassinate the generals. Sounds like trained assassins without all the guild stuff.
Well, since you've already house ruled and replaced the barbarian that has appeared in two editions of D&D so far, go for a third. I really doubt Barbarian =/= rage in Next.
So why does Barbarian (the class) get rage and not the dozens of people living in the barbarian culture? That's the spirit quest.
Actually, I have only house ruled one edition. I have not house ruled 4e, I refused to purchase or play it after borrowing some books and reading through it (Part of the reason was all of the house rules I would have had to implement). But yes, I would have house ruled the 4e barbarian starting with banning all of the elemental powers
Some of them are fighters, rogues, scouts, and such. A RANGER knows one of his his own vs. a common lightly armored warrior or hunter. A ranger is a mindset, an attitude, a common calling to protect and defend the land. He respects others who live by the bounty of the woods, but he knows those who live by the land and those who serve it.
There is no reason that it has to be that
Step 1: Ignore the fluff in the PHB.
Step 2: Insert your own.
Step 3: Create houserules to make it work (optional).
Nope, the designers should make it easy. Having a lightly armored warrior class trained with various weapons, stealth and armor, makes it easy to adapt to a number of concepts. If they create too much "story" and build mechanical features in to back it up then they risk creating too much work. And since 3e with their supplements, I tend not to like WOTC's fluff or mechanics built around it. Easier just not to buy another edition rather than trying to "fix" it.
Just don't make the default presentation dull as dishwater so as to dilute the terms into having no meaning. I'd much rather change or adapt the notion of rangers as having a common bond or heritage than to have ranger simply be a "archer or dual weilder nature skills" build without point or reason. I'd rather have fluff to change than no fluff at all.
My concern as noted above is they risk building in too many mechanics to back up the fluff making it too specific (draconic heritage sorcerer as gishes and even sorcerer manifestation itself).
The only reason that I ended up running 3e was Unearthed Arcana and some of the third party products that helped me to tailor classes by providing examples or provided me with classes to fit missing niches in a manner that I liked. Without those supplements, I would have liked much of the core 3e core mechanics and changes, but never ran or played it.