And Apple famously said they would never make a tablet smaller than 10", or a phone larger than 4".
Companies will gladly mislead people so that the buy today's product rather than wait for tomorrow. Unless there is a rather surprising update at WWDC about this then there will have to be a new Hue hub to support HomeKit due to the hardware requirement.
I would actually like to be wrong on this, as that means that other hubs could also work without new models (Wink, Staples Connect, etc). But everything I've seen involves the hardware requirement for hubs.
EDIT: Here is a snippet from the iOS Security Guide, HomeKit starts at page 20:
The security guide is here:
http://www.apple.com/business/docs/iOS_Security_Guide.pdf
Notice the bit about verifying the MFi certification? That's what the hardware chip does. And along with the encryption mentioned there, there is more encryption involved with the communication between the device and HomeKit. It is likely that the existing Philips Hue Hub doesn't have the processing power to handle the encryption.
As I stated before, Philips pushes everyone to use their API. If they told you you wouldn't need a new hub they may have been assuming their API would be able to work with HomeKit. Either way, unless the Product Manager of the Hue line told you that personally since about January or so likely the person you heard it from just didn't know any better.