Strange - that's almost exactly the opposite of how I feel - I'd only buy 4E if it was a major change. Why the heck would I want to buy an entire new set of books just to get minor changes I could implement myself?
Sure, I wouldn't mind buying one book for updates, but that isn't what would happen. First off, there's all three of the core books. And then the rest are going to follow, as surely as the Complete series replaced Sword & Fist, Tome & Blood, et all. Initially the attitude is that those books are still usable, just tweak them slightly. But then the replacement suppliments get released and the old books become distinctly non-core and even dodgy, to the extent that many DMs will consider any material from them invalid, even if it hasn't been replaced with an updated version.