Couldn't you buy the iPhone6s unlocked, then sell it for full price when the next iPhone comes out?

Wouldn't that be cheaper instead of paying for the monthly upgrade fees so you can get every new iPhone that comes out?

Added (1). when you buy it unlocked, does that mean you can choose to upgrade your phone whenever? Because you are under no contract right?

The monthly upgrade fees are typically for people who get applecare a lot, because it comes with it, so unless you never get applecare, then yes it is a little bit cheaper to sell your iPhone. Personally I hate selling it because I can never find anyone to sell it to, so I will definitely be taking advantage of this system once (hopefully) it reaches Canada