For real.
"Hey, I know this hasn't been released yet and has only been shown to the public (including you) a handful of times... But will this track my calorie consumption if I have an iPhone 5S that has Nike+ installed?!? ... No?!? Are you just stupid or did I incorrectly read that it would?!?"
Everyone seems to think that Apple retail has the same level of insight as Apple corporate. News flash, they don't. Heck, I have several friends in different departments at Apple corporate (Cupertino & Austin) and they were just as surprised by the Watch announcement as the rest of us outside the company. I mean, they had a feeling it was coming, just like the rest of the world, but that was their first glimpse of the actual device.
This whole ideology of tricking the Apple employee is just dumb. It'd be one thing if an engineer, who worked in the skunkworks area of Apple, missed a question. They designed and "built" the device/system. An Apple retail (and probably 90% of corporate) employee though? You might as well be asking your buddy who'll fix your computer for a 6 pack of beer. The only difference is they're much more knowledgable on trending repairs and issues since they deal with them all day.
/rant
To the original question, yes, it should work. If the Watch releases, and the proposed idea doesn't work, don't be surprised. There have been several system / device releases where planned features were dropped shortly before release without a public announcement. This is the main reason I tell the employees in my office to "wait and see" vs planning on some oddball feature being included.