We already know that 4E has exiled Druids, Half-Orcs, Bards, Gnomes, Monks, and many other core 3E options to later books. Today I read that the 4E PHB will have a greatly decreased selection of transmutation, necromancy, and illusion spells. Those will be in later books that feature necromancers, illusionists, and transmuters.
So what is clear is that the core PHB will not be enough to duplicate the options we enjoy now in a single 3E PHB.
I also read that they are throwing out the idea of "Core Rules" -- the later books will be "Core" too.
Clearly this is a business model that is designed to make you buy more books.
Also consider the much heavier emphasis on battles on grids with minis. Minis that Wizards will be happy to sell you, One reviewer has said: "The idea of the single, lone monster fight is almost entirely gone. 4E is about mobs." That is, mobs of minis that you are encouraged to buy.
I'm a cheapskate when it comes to gaming. In my entire life the ONLY non-core books I have bought are: the 1E Demigods and Dieties (the cool edition with the Cthulu Mythos), the 2E Psionics Handbook (deeply broken), Races of Faerun and Savage Species books (both for the wemic content). Oh, and the Book of Erotic Fantasy for my series on Sex in D&D (over-expensive and mostly flawed). And my wife gave me the 3.0 Tome and Blood splat book for a present. That's it! I don't buy minis. I don't buy games. I do buy the core books, though.
So as a very rare purchaser of game stuff, I am NOT the target demographic for Wizards of the Coast. They don't care about me -- after all, I contribute very little to the bottom line.
The game designers have clearly decided that they are targeting 4E to the gamer with an open wallet, who buys a new book every couple months, who buys minis, dice, modules, supplements, and who will be happy to subscribe to their (non-Mac-friendly) online gaming system.
A strong sign of this is that under 3E, you could play the game with the rules from the SRD for FREE. Under 4E, the so called SRD-equivalent will consist of an index with page number references so you can go look up rules in books.
So where does that leave me, looking ahead to 4E? Well, I won't say until the books come out and I can read actual reviews rather than newsgroup speculation. But let me tell you, I have a sick bad feeling about it.