Li Shenron
Legend
This conjures the image of dozens, nay hundreds of subclasses in oh so many splatbooks.
So, what I'm getting out of this is basically subclasses are the 5E version of kits/prestige classes/paragon paths.
Yep... The point is, one way or the other, there would always been dozens of splatbooks, tho not necessarily in the amount of 3e era (that depends on market prospects I guess). A year ago Mearls mentioned that prestige classes were probably coming back, eventually they found an alternative, but if they didn't do subclasses they would have done prestige classes or more core classes or something else.
Currently the 2 biggest design elements to fill splatbooks with are subclasses and feats. Of course spells and magic items also (and races and backgrounds possibly on an even smaller scale) but subclasses and feats are going to be the big character-defining options.
Remains to be seen if subclasses will be so dominant as to cannibalize feats in future products...
IMHO there are good reasons for sometimes designing something as subclass and some other times designing it as a feat (or feats chain), as I explained in this thread a week ago or so:
http://www.enworld.org/forum/showth...ses-and-Paragon-Paths-to-Subclasses-and-Feats