I don't have any problems with anything that might be considered a '4.5' for the simple fact that I don't believe hardcover copies of any 4.5 books will ever exist.
I fully believe that the current edition of D&D will continue to evolve, but it's main source of parsing out this evolution will be via D&D Insider. I think they will treat D&D the same exact way they do WoW (and other video games)... changing and balancing mechanics online so that there aren't books that need to be "repurchased". Online subscription and rules distribution will replace hardcover books.
If you own the original 4E hardcover books and enjoy that game as-is... you don't need to buy anything else to play a successful game (like the folks who own and just play Vanilla WoW). If, however, you find you play and enjoy D&D 4E enough that you want more to the experience... then you've probably already become (or should become) a D&D Insider to get all the extra and expanding stuff you just don't get from buying the first three books.
The only "reprinting" of book I might think they'd do is perhaps a yearly or bi-yearly softcover Rules update book like they are releasing with Essentials. Something that might only cost $15 bucks for those people who want a solid rules book to reference to, if getting stuff out of the DDI Compendium is too much of a hassle. But that rule book would by no means be required, as all the rules will eventually be online in an updated Compendium form.
4.5 won't be an all-new set of hardcover rulesbooks. It will be an updated set of DDI Tools that will include evolved and updated Rules Compendium, Character Builder and Adventure Tools (with Monster Builder, Encounter Builder, Trap Builder etc. etc.) And if you are already a DDI subscriber, you will get all this stuff for "free" as part of your subscription.