I'm starting to dread the general shift in the product line (before 4e is even out) toward what seems to be sourcebooks for every little thing (Chromatic dragons, Undead, etc) and the 'crunch creep' - where there's a feat here, a monster there, a paragon path over there, and so forth.
Ok, there will be an Undead sourcebook now? But since you're only adding classes to the game in the PHBs (oh, and the campaign settings' player's guides now, too, and whatever the next exception to the rule will be) and you're eventually going to add a Necromancer class, the "Undead Sourcebook" isn't exactly going to be definitive. You'd have to hold some of undead stuff back for future MMs and things like a Necro class, plus possibly the Divine sourcebook and other supplements. To make it marketable, I'd imagine you'd want to have a "something for everyone" appeal, so can we expect feats, powers, rituals and other characteristics in this sourcebook?
Even if these are only for monsters, at this rate it wouldn't take long before you're plumbing the depths of insanity for future Monster Manuals. "Monster Manual IV: Man-Eating Furniture!" (Oh, wait. Man-eating furniture is probably a supplement.) Why not just save it for the MM2?
I was really drawn to the concept that each year you'd have new core rulebooks to add to classes, races, monsters, power sources, and so forth... and then you'd have a only few books fleshing things out, like the power source books and the Adventurer's Vault-style books, the adventures, and the "setting of the year."
A book for Chromatic Dragons (first in a series), a book for Undead.... This is starting to make me feel a little queasy.
I thought they said 4e was going to have a tighter focus in terms of product line. Among other things, a tighter focus almost made things like proposed DDI subscription rates seem somewhat reasonable... two month's worth of subscription being about the same as a sourcebook every other month. But to ask your base to do both? I think they're making their own case against DDI here, in a sense. Ask a traditional D&D player if they'd rather have all the published material currently available or if they'd rather have a subscription to online tools and articles (when freeware tools and free message boards will probably work if one hunts them down), and they're going to pick the published material.