WWell I sent an email to Nike and they said they discontinued that app but looked at my account and suggested I let them forward it as a concern so that maybe the sensor technology will be brought back. Here's the response.
"Currently, there are no plans to make Nike+ iPod available on the iPhone 6 or 6+. Regarding the Running Sensor, it of course can still be used with iPhones older than the 6 and 6+, as well as iPod Touches and iPod Nanos that feature the Nike+ iPod App.
The Running App, which is available for the iPhone 6 and 6+, is designed to use a GPS signal when running outdoors, negating the need for a Running Sensor. When you run indoors with the Running App and disable the GPS feature, the app will rely solely on your iPhone's built-in accelerometer. No sensors required.
I see you’ve logged nearly 600 runs with Nike+ over the last 4 years, and that many of those have been recorded with Nike+ iPod. With that being said, I would be more than happy to take any feedback regarding the app and it not being available on the iPhone 6 and 6+, and ensure that the feedback reaches the appropriate department here at Nike. We take our consumers’ feedback very seriously, so please feel free to share it with us, because that feedback is what has lead to so many changes and innovations here at Nike over the years."