Go to this link to see how the optin/optout mechanism worked in the past:
http://www.amazon.com/gp/help/custom...deId=200671290
In the past there WAS a charge to opt out per this quote from that page:
"By unsubscribing, you will be charged for the price difference between your Kindle model and the corresponding Kindle with Special Offers model if your device was originally purchased at a subsidized price."
Thus, we still must await an official announcement from Amazon telling us if that option will be avaiable and what the charge, if any, will be to exercise it.