even if your ETF is waived, your upgrade still runs its course based on the last time you upgraded at the promotional rate.
I'm living proof of this.
When i moved from one state to another, the home address in which i reside at the new location was in roaming only (even according to the sprint.com coverage map).
For this reason, since they do not provide service at my service address, they let me out of the contract. However, this did not reset my rebate/upgrade eligibility, that is still based on 20 months from my original purchase date at promotional pricing.
The only exception to this rule is account services. They have the power to do whatever it takes in the retention of your patronage. Here is were you can be given the world coated in chocolate, or sent home with your tail between your legs.