WotC's job if not to create more classes

I'll be joining in a D&D Next game with my old time D&D buddies and have thus been taking a look at the Basic Rules. Although I've read quite a few comments regarding the "incompleteness" of the publication I'd question what's missing. Personally I find it quite complete. Particularly for a product that once sold with the slogan "Products of your imagination". What is WotC keeping back that is worth buying another book?

The basic rules include pretty much everything. Sure they have only 4 character classes and no character progression table nor in depth coverage of XP and levels. While some players may consider this incomplete, the rules have a rather complete set of weapons, armor and equipment. It also has a spell list that's big enough to last a couple of levels.

This begs me to ask what does WotC's consider an asset in this day and age of internet connectivity? The world model: character values, armor/weapon mechanics and values, combat mechanics and magic mechanics; or the instance values of a particular world: specific classes, specific spells, specific skills.

D&D is by no means a new game and publishing a new rules set with all the material that's already out there isn't going to keep players from looking into their own makeshift bard, or paladin, or archer or whatever. I could just pickup any of the classes I've played before and port them to D&D 5th. So what is WotC going to sell that would be worth buying?

I'll rephrase this looking at WotC's cash cow: MtG. MtG has rules for building a deck whereas D&D sells you the "whole deck" in the form of a class. The Basic Rules lack a set of rules to build classes and also lack class building blocks. How attractive would MtG be if WotC sold you a complete deck every time and you couldn't mix the cards? For example I bought the Fiery Dawn and Solitary Fiends intro decks; good as they were on their own I could mix them to create new decks and test them out.

Is there a class "building block" set of rules ready to be published sometime in the future? If not, why so? What would D&D look like if instead of selling player's handbooks with classes in them WotC sold class building blocks? The handbook would include class building rules and some sample classes.

Can a sense of scarcity be created with these blocks? In such a way that you need to have the "block" to actually be able to build a class around it. This is obviously something that would displease many players; a reminiscence of 4th's battle grids and a high $$ entry costs in tokens and figures, but one that may also please some who like to collect things. Not saying this is a good or smart idea. I'm just throwing wild thoughts out, but the fact is it is very uncommon to see players play with photocopied MtG cards.

To summarize, is WotC letting too much out of the bag with the Basic Rules and keeping too little for themselves in the form of classes? With basic information like combat and magic rules, equipment costs, weapon damage and armor effectiveness a great deal of the world's "model" is already handed to the players. Spells are more the "product of your imagination" kinda thing that can be easily filled in by the players and developed online through the internet.

Does the player's handbook include rules to build classes? Something like "you have 64 points", this power costs 5, that one 8, etc. Spells, abilities, races, features, etc. add up costs and then you have a finished class build from smaller individual elements. If not, then it seems like the "class" will continue to be D&D's atomic element; unlike MtG where a deck can be easily broken up and mixed together to create a new one as long as the basic deck building rules are followed.

Thoughts? Is there a place in D&D for a mechanism that stands between the class and the point buy models? Is it viable? Is there a business potential in it?