Will I be able to get the iPhone 6s Plus?

I have the 16GB iPhone 6 Plus for AT&T. I got it not long after they were released. With the upcoming release of the iPhone 6s and 6s Plus, will I be able to trade in my current 6 Plus for a new 6s Plus?

You may want to get in touch with AT&T, but there's no reason why you can't do an upgrade.

You can always trade it in and pay extra to upgrade.