The fact that Terry has publically said nothing means this isn't as cut and dried as a simple "he'll definitely be staying at Chelsea". If he was sure he'd be staying put we'd have seen him on SSN telling us so, not Ballack or Ancelotti or Kenyon talking about how committed he is to Chelsea.
There's obviously something to the rumours, whether that something materialises in Terry joining City or not is far from certain, but there's more to this story to come.
I'm still convinced he's more interested in a pay rise at Chelsea than a move to City, and that he's posturing in order to get one. However he might fancy the challenge/change of moving to Eastlands, or possibly he might be unable to get more money from Chelsea, or be unhappy with whatever they offer him. If I was abetting man I'd say it's not quite a 50/50 scenario at the moment, I'd say it's 70/30 in favour of him staying put.