It's also a bad idea to allow confirmation bias to be the determining factor in whether or not you believe them. Look at real evidence, not rumor. Right now there isn't any. You don't think mana nation has a vested interest in generating page hits by posting a rumor that could be using the conversations on this forum as their "source" for all we know? No rep in reliable D&D rumors. We do have some anecdotal reports from game store owners, but as a class, they are hideously misinformed.
This.
If wizards designed Essentials to be D&D4.5, they'd be marketing it as such.
They'd be marketing as a replacement to the old three-book set, they'd be damn sure to get that point across so that you will pay your money to grab it.
They wouldn't be marketing books in the old vien like Psionic Power, they wouldn't be teasing a new campaign setting designed in the old vien like Dark Sun, they'd be making sure that every bit of the Essentials would be letting you know it's the new way of doing things and that everything from now on will be going in that direction.
Instead... they're telling people that it's compatible with the base system, that it's a good entry point into the base system, that it includes some character variants that are different but are just fine with the base system...
...in other words, every single bit of marketing juice involving Essentials is subtly hinting that you buy the base system. "You don't have to... but why not?" is how Essentials is being plugged if you bother to read the marketing for it with a single -shred- of critical thought.
Ergo, it is reasonable to conclude that marketing is trying to use Essentials to create interest in old product, and what company bothers to do that if they did not continue planning to offer said old product?
If you're gonna be a cynic, at least use facts in your cynicism. This fear and loathing and sky is falling panic is stupid.