If I have an iPhone 5c, and my upgrade is in August, can I wait till September to get the iPhone 6s?

It hasn't been confirmed yet if the 6s will be out in September but if it does or even if it comes out in October, will I be able to upgrade to the newest one?
Or will I only be able to upgrade to the iPhone 6?
I wouldn't mind the 6 but the 6s will have a way better quality in picture and I love to take picture of my daughter.
So can I go from the 5c to the 6s?

My carrier is Sprint and I have he unlimited everything plan.

Once you're eligible for the upgrade, you can upgrade to any phone you want. There. No such restrictions.