HAHAHAHA! Discounts, like that is going to happen.
I'm certain that if/when they go to metered service it will be in 'tiered' packages so that the grandmas who use it to check email and surf the web will be paying the same or slightly more than their current amounts.
Something like this:
up to 50gb/month = same as current amount 50-100gb = 2x more 100-150gb = 3x more and so on
