D&D 4E 4.5E vs PHBII (4E)

I think Wizards did learn their lesson on 3.5E. However, as has been suggested, they need to introduce more core rule-like books in a few years to keep the numbers up. 3.5E was poo-pooed by fans (the idea and execution of it, I think the actual changes were applauded), however PHBII, DMGII and MMXXIV didn't raise the ire of fans (for good reason, they were only supplemental).

I think they'll introduce new versions of the core books, call them PHBII, etc, which contains some updated sections of the core books that need updating and add supplemental material along with it. The updated material will be optional changes, of course, so people can keep using the original rules, but a lot of players will want the updated rules and get the 'supplement' anyway.

Not a perfect solution, there'd still be a few grumblers, but it'd make a good compromise, I think.

Another thought: The upside to the DI is your new classes, races, spells, feats, from PHB II, III, etc. can be folded into your master "database" of what is available for you when you create electronic characters. As someone who currently uses eTools, this is a really useful feature when I'm putting together different kinds of bad guys and I'm looking for an unusual combination of abilities from different sources.