Every device probably will be going to get this feature, as it is not that hard to implement this on existing hardware.In wpcentral blog, they have mentioned it'll be available with Lumia denim update to 930,830 & 1520. No other phones mentioned
because they know that the device mentioned can easily run these features. What they don't want is to give false promises to anyone in case a technical fault occurs. This will outrage the people.